Как написать правильно млечный путь

Функционирует при финансовой поддержке Министерства цифрового развития, связи и массовых коммуникаций Российской Федерации

  • Словари
    • Проверка слова
    • Какие бывают словари
    • Аудиословарь «Русский устный»
    • Словари в Сети
  • Библиотека
    • Каталог
    • Читальный зал
    • Гостиная
  • Справка
    • Справочное бюро
    • Задать вопрос
    • Правила русской орфографии и пунктуации (1956)
    • Письмовник
  • Класс
    • Азбучные истины
    • Репетитор онлайн
    • Учебники
    • Олимпиады
    • Видео
    • Полезные ссылки
  • Лента
    • Новости
    • О чём говорят и пишут
    • Ближайшие конференции
    • Грамотный календарь
  • Игра
    • Игра «Балда»
    • Викторины
    • Конкурсы
    • Головоломки
    • Застольные игры
    • Загадки
  • Медиатека
    • Грамотные понедельники
    • Забытые классики
    • Что показывают
    • Реклама словаря
  • Поиск ответа
  • Горячие вопросы
  • Правила русской орфографии и пунктуации (1956)
  • Письмовник
  • Справочник по пунктуации
    • Предисловие
    • Структура словарной статьи
    • Приложение 1. Непервообразные предлоги
    • Приложение 2. Вводные слова и сочетания
    • Приложение 3. Составные союзы
    • Алфавитный список вводных слов и выражений
    • Список учебной и справочной литературы
    • Авторы
  • Справочник по фразеологии
  • Словарь трудностей
  • Словарь улиц Москвы
  • Непростые слова
  • Официальные документы
  • Книги о русском языке и лингвистике
    • Книги о лингвистике, языке и письменности
    • Лингвистические энциклопедии
    • Научно-популярные, научно-публицистические, художественно-научные книги о русском языке
  • Наша библиотека
  • Словарь языка интернета
  • Словарь трудностей русского языка для работников СМИ. Ударение, произношение, грамматические формы
  • Словарь Россия. Для туристов и не только
  • Словарь модных слов
  • Лингвокультурологический словарь. Английские литературные имена
  • Проект свода школьных орфографических правил

Поиск ответа

Всего найдено: 1

Как пишется слово «галактика» — с большой или маленькой буквы? Интересует сочетание в середине предложения «Галактика Млечный путь«.

Ответ справочной службы русского языка

Слово галактика в сочетании с названием нужно писать со строчной буквы, а слово путь – с прописной: галактика Млечный Путь. 

Источник

Как правильно пишется словосочетание «Млечный Путь»

Мле́чный Пу́ть

Мле́чный Пу́ть

Источник: Орфографический
академический ресурс «Академос» Института русского языка им. В.В. Виноградова РАН (словарная база
2020)

Делаем Карту слов лучше вместе

Привет! Меня зовут Лампобот, я компьютерная программа, которая помогает делать
Карту слов. Я отлично
умею считать, но пока плохо понимаю, как устроен ваш мир. Помоги мне разобраться!

Спасибо! Я стал чуточку лучше понимать мир эмоций.

Вопрос: умерять — это что-то нейтральное, положительное или отрицательное?

Ассоциации к словосочетанию «млечный путь»

Синонимы к словосочетанию «млечный путь»

Предложения со словосочетанием «Млечный Путь»

  • Через весь небосклон тянулся млечный путь необычайной густоты.
  • Млечный путь сиял на тёмном небе, и казалось, кто-то пролил кружку молока.
  • – Таинственные исчезновения космических кораблей в аномальных зонах «млечного пути» с две тысячи сто тридцать первого по две тысячи четыреста десятый год.
  • (все предложения)

Цитаты из русской классики со словосочетанием «Млечный Путь»

  • Лежа на спине, он ясно увидел, как прямая линия, образованная стеною и потолком, вдруг расцветилась радугой, изломалась и вся расплылась в мелких, как Млечный Путь, звездочках.
  • Ночь обещала быть холодной. По небу, усеянному звездами, широкой полосой протянулся Млечный Путь. Резкий, холодный ветер тянул с северо-запада. Я озяб и пошел в фанзу, а китаец остался один у огня.
  • Шубин не выходил из своей комнаты до самой ночи. Уже совсем стемнело, неполный месяц стоял высоко на небе, Млечный Путь забелел и звезды запестрели, когда Берсенев, простившись с Анной Васильевной, Еленой и Зоей, подошел к двери своего приятеля. Он нашел ее запертою и постучался.
  • (все
    цитаты из русской классики)

Значение словосочетания «млечный путь»

  • Мле́чный Путь (или Гала́ктика Млечный Путь) — галактика, в которой находятся Земля, Солнечная система и все отдельные звёзды, видимые невооружённым глазом. Относится к спиральным галактикам с перемычкой. (Википедия)

    Все значения словосочетания МЛЕЧНЫЙ ПУТЬ

Афоризмы русских писателей со словом «путь»

  • Нехитрое дело попасть ногою в проложенный след; гораздо труднее, но зато и почетнее, прокладывать путь самому.
  • Помни же, что путь у нас короче
    Тех путей, что намечает взгляд.
  • Идешь ты, ну и иди своим путем, не сворачивая в сторону. Прямо иди. Может, и не загинешь даром.
  • (все афоризмы русских писателей)

Отправить комментарий

Дополнительно

Источник

Млечный Путь

Млечный Путь

Мл’ечный П’уть

Русский орфографический словарь. / Российская академия наук. Ин-т рус. яз. им. В. В. Виноградова. — М.: «Азбуковник».
.
1999.

Синонимы:

Смотреть что такое «Млечный Путь» в других словарях:

  • Млечный путь — Галактика Млечный путь (компьютерная модель). Спиральная галактика с перемычкой. Доминируют два из четырёх рукавов. Характеристики Тип SBbc (спиральная галактика с баром) Диаме …   Википедия

  • МЛЕЧНЫЙ ПУТЬ — МЛЕЧНЫЙ ПУТЬ, слабосветящаяся полоса, видимая на небе в ясные темные ночи, проходящая по линии галактического экватора. Она образуется в результате свечения огромного количества звезд, в некоторых участках закрытых облаками межзвездного газа и… …   Научно-технический энциклопедический словарь

  • Млечный путь — широкая полоса на небѣ, состоящая изъ безчисленныхъ звѣздъ. Ср. Все небо усыпано весело мигающими звѣздами, и млечный путь вырисовывается такъ ясно, какъ будто его передъ праздникомъ помыли и потерли снѣгомъ. А. П. Чеховъ. Ванька. См. Моисеева… …   Большой толково-фразеологический словарь Михельсона (оригинальная орфография)

  • МЛЕЧНЫЙ ПУТЬ — МЛЕЧНЫЙ ПУТЬ, 1) пересекающая звездное небо неярко светящаяся полоса. Представляет собой огромное количество визуально неразличимых звезд, концентрирующихся к основной плоскости Галактики. Близ этой плоскости расположено Солнце, так что… …   Современная энциклопедия

  • МЛЕЧНЫЙ ПУТЬ — 1) пересекающая звездное небо неярко светящаяся полоса. Представляет собой огромное количество визуально неразличимых звезд, концентрирующихся к основной плоскости Галактики. Близ этой плоскости расположено Солнце, так что большинство звезд… …   Большой Энциклопедический словарь

  • Млечный Путь — МЛЕЧНЫЙ, ая, ое Толковый словарь Ожегова. С.И. Ожегов, Н.Ю. Шведова. 1949 1992 …   Толковый словарь Ожегова

  • МЛЕЧНЫЙ ПУТЬ — 1) Галактика. 2 )Светлая полоса на ночном небе проекция на небесную сферу удалённых (от Солнца) звёзд Галактики, близких к её плоскости. Повыш. яркость этой полосы обусловлена повыш. концентрацией звёзд в плоскости Галактики. Физическая… …   Физическая энциклопедия

  • млечный путь — сущ., кол во синонимов: 7 • батыева дорога (3) • галаксия (4) • галактика (24) …   Словарь синонимов

  • Млечный путь — МЛЕЧНЫЙ ПУТЬ, 1) пересекающая звездное небо неярко светящаяся полоса. Представляет собой огромное количество визуально неразличимых звезд, концентрирующихся к основной плоскости Галактики. Близ этой плоскости расположено Солнце, так что… …   Иллюстрированный энциклопедический словарь

  • Млечный Путь — У этого термина существуют и другие значения, см. Млечный Путь (значения). Млечный Путь Галактика …   Википедия

  • МЛЕЧНЫЙ ПУТЬ — туманное свечение на ночном небе от миллиардов звезд нашей Галактики. Полоса Млечного Пути опоясывает небосвод широким кольцом. Особенно хорошо Млечный Путь виден вдали от городских огней. В Северном полушарии его удобно наблюдать около полуночи… …   Энциклопедия Кольера

Источник
Milky Way
ESO-VLT-Laser-phot-33a-07.jpg

The Galactic Center as seen from Earth’s night sky (the laser creates a guide-star for the telescope)
Observation data (J2000 epoch)
Constellation Sagittarius
Right ascension 17h 45m 40.03599s[1]
Declination −29° 00′ 28.1699″[1]
Distance 7.935–8.277 kpc (25,881–26,996 ly)[2][3][4][a]
Characteristics
Type Sb; Sbc; SB(rs)bc[5][6]
Mass 1.15×1012[7] M☉
Number of stars 100–400 billion ((1–4)×1011)[9][10]
Size 26.8 ± 1.1 kpc (87,400 ± 3,590 ly)
(diameter; 25.0 mag/arcsec2 B-band isophote)[8]
Thickness of thin disk 220–450 pc (718–1,470 ly)[11]
Thickness of thick disk 2.6 ± 0.5 kpc (8,500 ± 1,600 ly)[11]
Angular momentum ≈1×1067 J s[12]
Sun’s Galactic rotation period 212 Myr[13]
Spiral pattern rotation period 220–360 Myr[14]
Bar pattern rotation period 160–180 Myr[15]
Speed relative to CMB rest frame 552.2±5.5 km/s[16]
Escape velocity at Sun’s position 550 km/s[17]
Dark matter density at Sun’s position 0.0088+0.0024
−0.0018 M☉pc−3 (0.35+0.08
−0.07 GeV cm−3)[17]

The Milky Way[b] is the galaxy that includes our Solar System, with the name describing the galaxy’s appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. The term Milky Way is a translation of the Latin via lactea, from the Greek γαλακτικός κύκλος (galaktikos kýklos), meaning «milky circle».[18][19][20] From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe.[21] Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Doust Curtis,[22] observations by Edwin Hubble showed that the Milky Way is just one of many galaxies.

The Milky Way is a barred spiral galaxy with an estimated D25 isophotal diameter of 26.8 ± 1.1 kiloparsecs (87,400 ± 3,590 light-years),[8] but only about 1,000 light years thick at the spiral arms (more at the bulge). Recent simulations suggest that a dark matter area, also containing some visible stars, may extend up to a diameter of almost 2 million light-years (613 kpc).[23][24] The Milky Way has several satellite galaxies and is part of the Local Group of galaxies, which form part of the Virgo Supercluster, which is itself a component of the Laniakea Supercluster.[25][26]

It is estimated to contain 100–400 billion stars[27][28] and at least that number of planets.[29][30] The Solar System is located at a radius of about 27,000 light-years (8.3 kpc) from the Galactic Center,[31] on the inner edge of the Orion Arm, one of the spiral-shaped concentrations of gas and dust. The stars in the innermost 10,000 light-years form a bulge and one or more bars that radiate from the bulge. The Galactic Center is an intense radio source known as Sagittarius A*, a supermassive black hole of 4.100 (± 0.034) million solar masses.[32][33] Stars and gases at a wide range of distances from the Galactic Center orbit at approximately 220 kilometers per second. The constant rotational speed appears to contradict the laws of Keplerian dynamics and suggests that much (about 90%)[34][35] of the mass of the Milky Way is invisible to telescopes, neither emitting nor absorbing electromagnetic radiation. This conjectural mass has been termed «dark matter».[36] The rotational period is about 212 million years at the radius of the Sun.[13]

The Milky Way as a whole is moving at a velocity of approximately 600 km per second with respect to extragalactic frames of reference. The oldest stars in the Milky Way are nearly as old as the Universe itself and thus probably formed shortly after the Dark Ages of the Big Bang.[37]

Etymology and mythology[edit]

The Origin of the Milky Way by Tintoretto (circa 1575–1580)

In the Babylonian epic poem Enūma Eliš, the Milky Way is created from the severed tail of the primeval salt water dragoness Tiamat, set in the sky by Marduk, the Babylonian national god, after slaying her.[38][39] This story was once thought to have been based on an older Sumerian version in which Tiamat is instead slain by Enlil of Nippur,[40][41] but is now thought to be purely an invention of Babylonian propagandists with the intention to show Marduk as superior to the Sumerian deities.[41]

In Greek mythology, Zeus places his son born by a mortal woman, the infant Heracles, on Hera’s breast while she is asleep so the baby will drink her divine milk and thus become immortal. Hera wakes up while breastfeeding and then realizes she is nursing an unknown baby: she pushes the baby away, some of her milk spills, and it produces the band of light known as the Milky Way. In another Greek story, the abandoned Heracles is given by Athena to Hera for feeding, but Heracles’ forcefulness causes Athena to rip him from her breast in pain.[42][43][44]

Llys Dôn (literally «The Court of Dôn») is the traditional Welsh name for the constellation Cassiopeia. At least three of Dôn’s children also have astronomical associations: Caer Gwydion («The fortress of Gwydion») is the traditional Welsh name for the Milky Way,[45][46] and Caer Arianrhod («The Fortress of Arianrhod») being the constellation of Corona Borealis.[47][48]

In western culture, the name «Milky Way» is derived from its appearance as a dim un-resolved «milky» glowing band arching across the night sky. The term is a translation of the Classical Latin via lactea, in turn derived from the Hellenistic Greek γαλαξίας, short for γαλαξίας κύκλος (galaxías kýklos), meaning «milky circle». The Ancient Greek γαλαξίας (galaxias) – from root γαλακτ-, γάλα («milk») + -ίας (forming adjectives) – is also the root of «galaxy», the name for our, and later all such, collections of stars.[18][49][50][51]

The Milky Way, or «milk circle», was just one of 11 «circles» the Greeks identified in the sky, others being the zodiac, the meridian, the horizon, the equator, the tropics of Cancer and Capricorn, the Arctic Circle and the Antarctic Circle, and two colure circles passing through both poles.[52]

Appearance[edit]

The Milky Way is visible as a hazy band of white light, some 30° wide, arching the night sky.[53] Although all the individual naked-eye stars in the entire sky are part of the Milky Way Galaxy, the term «Milky Way» is limited to this band of light.[54][55] The light originates from the accumulation of unresolved stars and other material located in the direction of the galactic plane. Brighter regions around the band appear as soft visual patches known as star clouds. The most conspicuous of these is the Large Sagittarius Star Cloud, a portion of the central bulge of the galaxy.[56] Dark regions within the band, such as the Great Rift and the Coalsack, are areas where interstellar dust blocks light from distant stars. Peoples of the southern hemisphere, including the Inca and Australian aborigines, identified these regions as dark cloud constellations.[57] The area of sky that the Milky Way obscures is called the Zone of Avoidance.[58]

The Milky Way has a relatively low surface brightness. Its visibility can be greatly reduced by background light, such as light pollution or moonlight. The sky needs to be darker than about 20.2 magnitude per square arcsecond in order for the Milky Way to be visible.[59] It should be visible if the limiting magnitude is approximately +5.1 or better and shows a great deal of detail at +6.1.[60] This makes the Milky Way difficult to see from brightly lit urban or suburban areas, but very prominent when viewed from rural areas when the Moon is below the horizon.[c] Maps of artificial night sky brightness show that more than one-third of Earth’s population cannot see the Milky Way from their homes due to light pollution.[61]

As viewed from Earth, the visible region of the Milky Way’s galactic plane occupies an area of the sky that includes 30 constellations.[d] The Galactic Center lies in the direction of Sagittarius, where the Milky Way is brightest. From Sagittarius, the hazy band of white light appears to pass around to the galactic anticenter in Auriga. The band then continues the rest of the way around the sky, back to Sagittarius, dividing the sky into two roughly equal hemispheres.[citation needed]

The galactic plane is inclined by about 60° to the ecliptic (the plane of Earth’s orbit). Relative to the celestial equator, it passes as far north as the constellation of Cassiopeia and as far south as the constellation of Crux, indicating the high inclination of Earth’s equatorial plane and the plane of the ecliptic, relative to the galactic plane. The north galactic pole is situated at right ascension 12h 49m, declination +27.4° (B1950) near β Comae Berenices, and the south galactic pole is near α Sculptoris. Because of this high inclination, depending on the time of night and year, the Milky Way arch may appear relatively low or relatively high in the sky. For observers from latitudes approximately 65° north to 65° south, the Milky Way passes directly overhead twice a day.[citation needed]

  • The Milky Way arching at a high inclination across the night sky, (this composited panorama was taken at Paranal Observatory in northern Chile); the Magellanic Clouds can be seen on the left; the bright object near top center is Jupiter in the constellation Sagittarius, and the orange glow at the horizon on the right is Antofagasta city with a jet trail above it; galactic north is downward.

    The Milky Way arching at a high inclination across the night sky, (this composited panorama was taken at Paranal Observatory in northern Chile); the Magellanic Clouds can be seen on the left; the bright object near top center is Jupiter in the constellation Sagittarius, and the orange glow at the horizon on the right is Antofagasta city with a jet trail above it; galactic north is downward.

  • The Milky Way viewed at different wavelengths

    The Milky Way viewed at different wavelengths

Astronomical history[edit]

The shape of the Milky Way as deduced from star counts by William Herschel in 1785; the Solar System was assumed near center

In Meteorologica, Aristotle (384–322 BC) states that the Greek philosophers Anaxagoras (c. 500–428 BC) and Democritus (460–370 BC) proposed that the Milky Way is the glow of stars not directly visible due to Earth’s shadow, while other stars receive their light from the Sun (but have their glow obscured by solar rays).[62] Aristotle himself believed that the Milky Way was part of the Earth’s upper atmosphere (along with the stars), and that it was a byproduct of stars burning that did not dissipate because of its outermost location in the atmosphere (composing its great circle). He also said that the Milky appearance of the Milky Way galaxy was due to the refraction of the earth’s atmosphere.[63][64][65] The Neoplatonist philosopher Olympiodorus the Younger (c. 495–570 AD) criticized this view, arguing that if the Milky Way were sublunary, it should appear different at different times and places on Earth, and that it should have parallax, which it does not. In his view, the Milky Way is celestial. This idea would be influential later in the Muslim world.[66]

The Persian astronomer Al-Biruni (973–1048) proposed that the Milky Way is «a collection of countless fragments of the nature of nebulous stars».[67] The Andalusian astronomer Avempace (d 1138) proposed the Milky Way to be made up of many stars but appears to be a continuous image in the Earth’s atmosphere, citing his observation of a conjunction of Jupiter and Mars in 1106 or 1107 as evidence.[64] The Persian astronomer Nasir al-Din al-Tusi (1201–1274) in his Tadhkira wrote: «The Milky Way, i.e. the Galaxy, is made up of a very large number of small, tightly clustered stars, which, on account of their concentration and smallness, seem to be cloudy patches. Because of this, it was likened to milk in color.»[68] Ibn Qayyim al-Jawziyya (1292–1350) proposed that the Milky Way is «a myriad of tiny stars packed together in the sphere of the fixed stars».[69]

Proof of the Milky Way consisting of many stars came in 1610 when Galileo Galilei used a telescope to study the Milky Way and discovered that it is composed of a huge number of faint stars. Galileo also concluded that the appearance of the Milky Way was due to refraction of the Earth’s atmosphere .[70][71][63] In a treatise in 1755, Immanuel Kant, drawing on earlier work by Thomas Wright,[72] speculated (correctly) that the Milky Way might be a rotating body of a huge number of stars, held together by gravitational forces akin to the Solar System but on much larger scales.[73] The resulting disk of stars would be seen as a band on the sky from our perspective inside the disk. Wright and Kant also conjectured that some of the nebulae visible in the night sky might be separate «galaxies» themselves, similar to our own. Kant referred to both the Milky Way and the «extragalactic nebulae» as «island universes», a term still current up to the 1930s.[74][75][76]

The first attempt to describe the shape of the Milky Way and the position of the Sun within it was carried out by William Herschel in 1785 by carefully counting the number of stars in different regions of the visible sky. He produced a diagram of the shape of the Milky Way with the Solar System close to the center.[77]

In 1845, Lord Rosse constructed a new telescope and was able to distinguish between elliptical and spiral-shaped nebulae. He also managed to make out individual point sources in some of these nebulae, lending credence to Kant’s earlier conjecture.[78][79]

Photograph of the «Great Andromeda Nebula» from 1899, later identified as the Andromeda Galaxy

In 1904, studying the proper motions of stars, Jacobus Kapteyn reported that these were not random, as it was believed in that time; stars could be divided into two streams, moving in nearly opposite directions.[80] It was later realized that Kapteyn’s data had been the first evidence of the rotation of our galaxy,[81] which ultimately led to the finding of galactic rotation by Bertil Lindblad and Jan Oort.[citation needed]

In 1917, Heber Curtis had observed the nova S Andromedae within the Great Andromeda Nebula (Messier object 31). Searching the photographic record, he found 11 more novae. Curtis noticed that these novae were, on average, 10 magnitudes fainter than those that occurred within the Milky Way. As a result, he was able to come up with a distance estimate of 150,000 parsecs. He became a proponent of the «island universes» hypothesis, which held that the spiral nebulae were independent galaxies.[82][83] In 1920 the Great Debate took place between Harlow Shapley and Heber Curtis, concerning the nature of the Milky Way, spiral nebulae, and the dimensions of the Universe. To support his claim that the Great Andromeda Nebula is an external galaxy, Curtis noted the appearance of dark lanes resembling the dust clouds in the Milky Way, as well as the significant Doppler shift.[84]

The controversy was conclusively settled by Edwin Hubble in the early 1920s using the Mount Wilson observatory 2.5 m (100 in) Hooker telescope. With the light-gathering power of this new telescope, he was able to produce astronomical photographs that resolved the outer parts of some spiral nebulae as collections of individual stars. He was also able to identify some Cepheid variables that he could use as a benchmark to estimate the distance to the nebulae. He found that the Andromeda Nebula is 275,000 parsecs from the Sun, far too distant to be part of the Milky Way.[85][86]

Astrography[edit]

An all-sky view of stars in the Milky Way and neighbouring galaxies, based on the first year of observations from Gaia satellite, from July 2014 to September 2015. The map shows the density of stars in each portion of the sky. Brighter regions indicate denser concentrations of stars. Darker regions across the Galactic Plane correspond to dense clouds of interstellar gas and dust that absorb starlight.

The ESA spacecraft Gaia provides distance estimates by determining the parallax of a billion stars and is mapping the Milky Way with four planned releases of maps in 2016, 2018, 2021 and 2024.[87][88]
Data from Gaia has been described as «transformational». It has been estimated that Gaia has expanded the number of observations of stars from about 2 million stars as of the 1990s to 2 billion. It has expanded the measurable volume of space by a factor of 100 in radius and a factor of 1,000 in precision.[89]
A study in 2020 concluded that Gaia detected a wobbling motion of the galaxy, which might be caused by «torques from a misalignment of the disc’s rotation axis with respect to the principal axis of a non-spherical halo, or from accreted matter in the halo acquired during late infall, or from nearby, interacting satellite galaxies and their consequent tides».[90]

Sun’s location and neighborhood[edit]

Position of the Solar System within the Milky Way

Diagram of the Milky Way with the position of the Solar System marked by a yellow arrow and a red dot in the Orion Arm. The dot roughly covers the larger surroundings of the Solar System, the space between the Radcliffe wave and Split linear structures (formerly the Gould Belt).[91]

Artistic close-up of the Orion Arm with the main features of the Radcliffe Wave and Split linear structures, and with the Solar System surrounded by the closest large scale celestial features at the surface of the Local Bubble at a distance of 400–500 light years.

The Sun is near the inner rim of the Orion Arm, within the Local Fluff of the Local Bubble, between the Radcliffe wave and Split linear structures (formerly Gould Belt).[91] Based upon studies of stellar orbits around Sgr A* by Gillessen et al. (2016), the Sun lies at an estimated distance of 27.14 ± 0.46 kly (8.32 ± 0.14 kpc)[31] from the Galactic Center. Boehle et al. (2016) found a smaller value of 25.64 ± 0.46 kly (7.86 ± 0.14 kpc), also using a star orbit analysis.[92] The Sun is currently 5–30 parsecs (16–98 ly) above, or north of, the central plane of the Galactic disk.[93] The distance between the local arm and the next arm out, the Perseus Arm, is about 2,000 parsecs (6,500 ly).[94] The Sun, and thus the Solar System, is located in the Milky Way’s galactic habitable zone.[95][96]

There are about 208 stars brighter than absolute magnitude 8.5 within a sphere with a radius of 15 parsecs (49 ly) from the Sun, giving a density of one star per 69 cubic parsecs, or one star per 2,360 cubic light-years (from List of nearest bright stars). On the other hand, there are 64 known stars (of any magnitude, not counting 4 brown dwarfs) within 5 parsecs (16 ly) of the Sun, giving a density of about one star per 8.2 cubic parsecs, or one per 284 cubic light-years (from List of nearest stars). This illustrates the fact that there are far more faint stars than bright stars: in the entire sky, there are about 500 stars brighter than apparent magnitude 4 but 15.5 million stars brighter than apparent magnitude 14.[97]

The apex of the Sun’s way, or the solar apex, is the direction that the Sun travels through space in the Milky Way. The general direction of the Sun’s Galactic motion is towards the star Vega near the constellation of Hercules, at an angle of roughly 60 sky degrees to the direction of the Galactic Center. The Sun’s orbit about the Milky Way is expected to be roughly elliptical with the addition of perturbations due to the Galactic spiral arms and non-uniform mass distributions. In addition, the Sun passes through the Galactic plane approximately 2.7 times per orbit.[98] This is very similar to how a simple harmonic oscillator works with no drag force (damping) term. These oscillations were until recently thought to coincide with mass lifeform extinction periods on Earth.[99] A reanalysis of the effects of the Sun’s transit through the spiral structure based on CO data has failed to find a correlation.[100]

It takes the Solar System about 240 million years to complete one orbit of the Milky Way (a galactic year),[101] so the Sun is thought to have completed 18–20 orbits during its lifetime and 1/1250 of a revolution since the origin of humans. The orbital speed of the Solar System about the center of the Milky Way is approximately 220 km/s (490,000 mph) or 0.073% of the speed of light. The Sun moves through the heliosphere at 84,000 km/h (52,000 mph). At this speed, it takes around 1,400 years for the Solar System to travel a distance of 1 light-year, or 8 days to travel 1 AU (astronomical unit).[102] The Solar System is headed in the direction of the zodiacal constellation Scorpius, which follows the ecliptic.[103]

Galactic quadrants[edit]

A galactic quadrant, or quadrant of the Milky Way, refers to one of four circular sectors in the division of the Milky Way. In astronomical practice, the delineation of the galactic quadrants is based upon the galactic coordinate system, which places the Sun as the origin of the mapping system.[104]

Quadrants are described using ordinals – for example, «1st galactic quadrant»,[105] «second galactic quadrant»,[106] or «third quadrant of the Milky Way».[107] Viewing from the north galactic pole with 0° (zero degrees) as the ray that runs starting from the Sun and through the Galactic Center, the quadrants are:

Galactic
quadrant
  		Galactic
longitude
(ℓ) 		 
Reference
 
1st 0° ≤ ℓ ≤ 90°   [108]
2nd   90° ≤ ℓ ≤ 180° [106]
3rd 180° ≤ ℓ ≤ 270° [107]
4th
  		270° ≤ ℓ ≤ 360°
(360° ≅ 0°) 		[105]
 

with the galactic longitude (ℓ) increasing in the counter-clockwise direction (positive rotation) as viewed from north of the Galactic Center (a view-point several hundred thousand light-years distant from Earth in the direction of the constellation Coma Berenices); if viewed from south of the Galactic Center (a view-point similarly distant in the constellation Sculptor), ℓ would increase in the clockwise direction (negative rotation).

Size and mass[edit]

The structure of the Milky Way is thought to be similar to this galaxy (UGC 12158 imaged by Hubble)

Size[edit]

A size comparison of the six largest galaxies of the Local Group, together with the Milky Way

The Milky Way is one of the two largest galaxies in the Local Group (the other being the Andromeda Galaxy), although the size for its galactic disc and how much it defines the isophotal diameter is not well understood.[109] It is estimated that the significant bulk of stars in the galaxy lies within the 26 kiloparsecs (80,000 light-years) diameter, and that the number of stars beyond the outermost disc dramatically reduces to a very low number, with respect to an extrapolation of the exponential disk with the scale length of the inner disc.[110][109]

There are several methods being used in astronomy in defining the size of a galaxy, and each of them can yield different results with respect to one another. The most commonly employed method is the D25 standard – the isophote where the photometric brightness of a galaxy in the B-band (445 nm wavelength of light, in the blue part of the visible spectrum) reaches 25 mag/arcsec2.[111] An estimate from 1997 by Goodwin and others compared the distribution of Cepheid variable stars in 17 other spiral galaxies to the ones in the Milky Way, and modelling the relationship to their surface brightnesses. This gave an isophotal diameter for the Milky Way at 26.8 ± 1.1 kiloparsecs (87,400 ± 3,590 light-years), by assuming that the galactic disc is well represented by an exponential disc and adopting a central surface brightness of the galaxy (µ0) of 22.1±0.3 B-mag/arcsec−2 and a disk scale length (h) of 5.0 ± 0.5 kpc (16,000 ± 1,600 ly).[112][8][113] This is significantly smaller than the Andromeda Galaxy’s isophotal diameter, and slightly below the mean isophotal sizes of the galaxies being at 28.3 kpc (92,000 ly).[8] The paper concludes that the Milky Way and Andromeda Galaxy were not overly large spiral galaxies and as well as one of the largest known (if the former not being the largest) as previously widely believed, but rather average ordinary spiral galaxies.[114] To compare the relative physical scale of the Milky Way, if the Solar System out to Neptune were the size of a US quarter (24.3 mm (0.955 in)), the Milky Way would be approximately at least the greatest north–south line of the contiguous United States.[115] An even older study from 1978 gave a lower diameter for Milky Way about 23 kpc (75,000 ly).[8]

A 2015 paper discovered that there is a ring-like filament of stars called Triangulum–Andromeda Ring (TriAnd Ring) rippling above and below the relatively flat galactic plane, which alongside Monoceros Ring were both suggested to be primarily the result of disk oscillations and wrapping around the Milky Way, at a diameter of at least 50 kpc (160,000 ly),[116] which may be part of the Milky Way’s outer disk itself, hence making the stellar disk larger by increasing to this size.[117] However, a more recent 2018 paper later somewhat ruled out this hypothesis, and supported a conclusion that the Monoceros Ring, A13 and TriAnd Ring were stellar overdensities rather kicked out from the main stellar disk, with the velocity dispersion of the RR Lyrae stars found to be higher and consistent with halo membership.[118] Another 2018 study revealed the very probable presence of disk stars at 26–31.5 kpc (84,800–103,000 ly) from the Galactic Center or perhaps even farther, significantly beyond approximately 13–20 kpc (40,000–70,000 ly), in which it was once believed to be the abrupt drop-off of the stellar density of the disk, meaning that few or no stars were expected to be above this limit, save for stars that belong to the old population of the galactic halo.[109][119][120]

A 2020 study predicted the edge of the Milky Way’s dark matter halo being around 292 ± 61 kpc (952,000 ± 199,000 ly), which translates to a diameter of 584 ± 122 kpc (1.905 ± 0.3979 Mly).[23][24] The Milky Way’s stellar disk is also estimated to be approximately up to 1.35 kpc (4,000 ly) thick.[121][122]

A schematic profile of the Milky Way.
Abbreviations: GNP/GSP: Galactic North and South Poles

Mass[edit]

The Milky Way is approximately 890 billion to 1.54 trillion times the mass of the Sun in total (8.9×1011 to 1.54×1012 solar masses),[34][35][123] although stars and planets make up only a small part of this. Estimates of the mass of the Milky Way vary, depending upon the method and data used. The low end of the estimate range is 5.8×1011 solar masses (M☉), somewhat less than that of the Andromeda Galaxy.[124][125][126] Measurements using the Very Long Baseline Array in 2009 found velocities as large as 254 km/s (570,000 mph) for stars at the outer edge of the Milky Way.[127] Because the orbital velocity depends on the total mass inside the orbital radius, this suggests that the Milky Way is more massive, roughly equaling the mass of Andromeda Galaxy at 7×1011 M☉ within 160,000 ly (49 kpc) of its center.[128] In 2010, a measurement of the radial velocity of halo stars found that the mass enclosed within 80 kiloparsecs is 7×1011 M☉.[129] According to a study published in 2014, the mass of the entire Milky Way is estimated to be 8.5×1011 M☉,[130] but this is only half the mass of the Andromeda Galaxy.[130] A recent 2019 mass estimate for the Milky Way is 1.29×1012 M☉.[131]

Much of the mass of the Milky Way seems to be dark matter, an unknown and invisible form of matter that interacts gravitationally with ordinary matter. A dark matter halo is conjectured to spread out relatively uniformly to a distance beyond one hundred kiloparsecs (kpc) from the Galactic Center. Mathematical models of the Milky Way suggest that the mass of dark matter is 1–1.5×1012 M☉.[132][133][134] 2013 and 2014 studies indicate a range in mass, as large as 4.5×1012 M☉[135] and as small as 8×1011 M☉.[136] By comparison, the total mass of all the stars in the Milky Way is estimated to be between 4.6×1010 M☉[137] and 6.43×1010 M☉.[132] In addition to the stars, there is also interstellar gas, comprising 90% hydrogen and 10% helium by mass,[138] with two thirds of the hydrogen found in the atomic form and the remaining one-third as molecular hydrogen.[139] The mass of the Milky Way’s interstellar gas is equal to between 10%[139] and 15%[138] of the total mass of its stars. Interstellar dust accounts for an additional 1% of the total mass of the gas.[138]

In March 2019, astronomers reported that the virial mass of the Milky Way galaxy is 1.54 trillion solar masses within a radius of about 39.5 kpc (130,000 ly), over twice as much as was determined in earlier studies, and suggesting that about 90% of the mass of the galaxy is dark matter.[34][35]

Contents[edit]

360-degree panorama view of the Milky Way (an assembled mosaic of photographs) by ESO, the galactic centre is in the middle of the view, with galactic north up

360-degree rendering of the Milky Way using Gaia EDR3 data showing interstellar gas, dust backlit by stars (main patches labeled in black; white labels are main bright patches of stars). Left hemisphere is facing the galactic center, right hemisphere is facing the galactic anticenter.

The Milky Way contains between 100 and 400 billion stars[9][10] and at least that many planets.[140] An exact figure would depend on counting the number of very-low-mass stars, which are difficult to detect, especially at distances of more than 300 ly (90 pc) from the Sun. As a comparison, the neighboring Andromeda Galaxy contains an estimated one trillion (1012) stars.[141] The Milky Way may contain ten billion white dwarfs, a billion neutron stars, and a hundred million stellar black holes.[e][142][143] Filling the space between the stars is a disk of gas and dust called the interstellar medium. This disk has at least a comparable extent in radius to the stars,[144] whereas the thickness of the gas layer ranges from hundreds of light-years for the colder gas to thousands of light-years for warmer gas.[145][146]

The disk of stars in the Milky Way does not have a sharp edge beyond which there are no stars. Rather, the concentration of stars decreases with distance from the center of the Milky Way. For reasons that are not understood, beyond a radius of roughly 40,000 light years (13 kpc) from the center, the number of stars per cubic parsec drops much faster with radius.[110] Surrounding the galactic disk is a spherical galactic halo of stars and globular clusters that extends farther outward, but is limited in size by the orbits of two Milky Way satellites, the Large and Small Magellanic Clouds, whose closest approach to the Galactic Center is about 180,000 ly (55 kpc).[147] At this distance or beyond, the orbits of most halo objects would be disrupted by the Magellanic Clouds. Hence, such objects would probably be ejected from the vicinity of the Milky Way. The integrated absolute visual magnitude of the Milky Way is estimated to be around −20.9.[148][149][f]

Both gravitational microlensing and planetary transit observations indicate that there may be at least as many planets bound to stars as there are stars in the Milky Way,[29][150] and microlensing measurements indicate that there are more rogue planets not bound to host stars than there are stars.[151][152] The Milky Way contains at least one planet per star, resulting in 100–400 billion planets, according to a January 2013 study of the five-planet star system Kepler-32 by the Kepler space observatory.[30] A different January 2013 analysis of Kepler data estimated that at least 17 billion Earth-sized exoplanets reside in the Milky Way.[153] On November 4, 2013, astronomers reported, based on Kepler space mission data, that there could be as many as 40 billion Earth-sized planets orbiting in the habitable zones of Sun-like stars and red dwarfs within the Milky Way.[154][155][156] 11 billion of these estimated planets may be orbiting Sun-like stars.[157] The nearest exoplanet may be 4.2 light-years away, orbiting the red dwarf Proxima Centauri, according to a 2016 study.[158] Such Earth-sized planets may be more numerous than gas giants,[29] though harder to detect at great distances given their small size. Besides exoplanets, «exocomets», comets beyond the Solar System, have also been detected and may be common in the Milky Way.[159] More recently, in November 2020, over 300 million habitable exoplanets are estimated to exist in the Milky Way Galaxy.[160]

Structure[edit]

Overview of different elements of the overall structure of the Milky Way.

A dark spot surrounded by doughnut shaped orange-yellow ring

Artist’s impression of how the Milky Way would look from different vantage points – from edge-on lines-of-sight, the peanut-shell-shaped structure, not to be confused with the galaxy’s central bulge, is evident; viewed from above, the central narrow bar that is responsible for this structure appears clearly, as would many spiral arms and their associated dust clouds

The Milky Way consists of a bar-shaped core region surrounded by a warped disk of gas, dust and stars.[162][163] The mass distribution within the Milky Way closely resembles the type Sbc in the Hubble classification, which represents spiral galaxies with relatively loosely wound arms.[5] Astronomers first began to conjecture that the Milky Way is a barred spiral galaxy, rather than an ordinary spiral galaxy, in the 1960s.[164][165][166] These conjectures were confirmed by the Spitzer Space Telescope observations in 2005 that showed the Milky Way’s central bar to be larger than previously thought.[167]

Galactic Center[edit]

The Sun is 25,000–28,000 ly (7.7–8.6 kpc) from the Galactic Center. This value is estimated using geometric-based methods or by measuring selected astronomical objects that serve as standard candles, with different techniques yielding various values within this approximate range.[168][92][31][169][170][171] In the inner few kiloparsecs (around 10,000 light-years radius) is a dense concentration of mostly old stars in a roughly spheroidal shape called the bulge.[172] It has been proposed that the Milky Way lacks a bulge due to a collision and merger between previous galaxies, and that instead it only has a pseudobulge formed by its central bar.[173] However, confusion in the literature between the (peanut shell)-shaped structure created by instabilities in the bar, versus a possible bulge with an expected half-light radius of 0.5 kpc, abounds.[174]

The Galactic Center is marked by an intense radio source named Sagittarius A* (pronounced Sagittarius A-star). The motion of material around the center indicates that Sagittarius A* harbors a massive, compact object.[175] This concentration of mass is best explained as a supermassive black hole[g][168][176] (SMBH) with an estimated mass of 4.1–4.5 million times the mass of the Sun.[176] The rate of accretion of the SMBH is consistent with an inactive galactic nucleus, being estimated at 1×10−5 M☉ per year.[177] Observations indicate that there are SMBHs located near the center of most normal galaxies.[178][179]

The nature of the Milky Way’s bar is actively debated, with estimates for its half-length and orientation spanning from 1 to 5 kpc (3,000–16,000 ly) and 10–50 degrees relative to the line of sight from Earth to the Galactic Center.[170][171][180] Certain authors advocate that the Milky Way features two distinct bars, one nestled within the other.[181] However, RR Lyrae-type stars do not trace a prominent Galactic bar.[171][182][183] The bar may be surrounded by a ring called the «5 kpc ring» that contains a large fraction of the molecular hydrogen present in the Milky Way, as well as most of the Milky Way’s star formation activity. Viewed from the Andromeda Galaxy, it would be the brightest feature of the Milky Way.[184] X-ray emission from the core is aligned with the massive stars surrounding the central bar[177] and the Galactic ridge.[185]

Gamma rays and x-rays[edit]

Since 1970, various gamma-ray detection missions have discovered 511-keV gamma rays coming from the general direction of the Galactic Center. These gamma rays are produced by positrons (antielectrons) annihilating with electrons. In 2008 it was found that the distribution of the sources of the gamma rays resembles the distribution of low-mass X-ray binaries, seeming to indicate that these X-ray binaries are sending positrons (and electrons) into interstellar space where they slow down and annihilate.[186][187][188] The observations were both made by NASA and ESA’s satellites. In 1970 gamma ray detectors found that the emitting region was about 10,000 light-years across with a luminosity of about 10,000 suns.[187]

Illustration of the two gigantic X-ray/gamma-ray bubbles (blue-violet) of the Milky Way (center)

In 2010, two gigantic spherical bubbles of high energy gamma-emission were detected to the north and the south of the Milky Way core, using data from the Fermi Gamma-ray Space Telescope. The diameter of each of the bubbles is about 25,000 light-years (7.7 kpc) (or about 1/4 of the galaxy’s estimated diameter); they stretch up to Grus and to Virgo on the night-sky of the southern hemisphere.[189][190] Subsequently, observations with the Parkes Telescope at radio frequencies identified polarized emission that is associated with the Fermi bubbles. These observations are best interpreted as a magnetized outflow driven by star formation in the central 640 ly (200 pc) of the Milky Way.[191]

Later, on January 5, 2015, NASA reported observing an X-ray flare 400 times brighter than usual, a record-breaker, from Sagittarius A*. The unusual event may have been caused by the breaking apart of an asteroid falling into the black hole or by the entanglement of magnetic field lines within gas flowing into Sagittarius A*.[161]

Spiral arms[edit]

Outside the gravitational influence of the Galactic bar, the structure of the interstellar medium and stars in the disk of the Milky Way is organized into four spiral arms.[192] Spiral arms typically contain a higher density of interstellar gas and dust than the Galactic average as well as a greater concentration of star formation, as traced by H II regions[193][194] and molecular clouds.[195]

The Milky Way’s spiral structure is uncertain, and there is currently no consensus on the nature of the Milky Way’s arms.[196] Perfect logarithmic spiral patterns only crudely describe features near the Sun,[194][197] because galaxies commonly have arms that branch, merge, twist unexpectedly, and feature a degree of irregularity.[171][197][198] The possible scenario of the Sun within a spur / Local arm[194] emphasizes that point and indicates that such features are probably not unique, and exist elsewhere in the Milky Way.[197] Estimates of the pitch angle of the arms range from about 7° to 25°.[144][199] There are thought to be four spiral arms that all start near the Milky Way Galaxy’s center.[200] These are named as follows, with the positions of the arms shown in the image below:

Observed (normal lines) and extrapolated (dotted lines) structure of the spiral arms of the Milky Way, viewed from north of the galaxy – the galaxy rotates clockwise in this view. The gray lines radiating from the Sun’s position (upper center) list the three-letter abbreviations of the corresponding constellations

Color Arm(s)
turquoise Near 3 kpc Arm and Perseus Arm
blue Norma and Outer arm (Along with extension discovered in 2004[201])
green Scutum–Centaurus Arm
red Carina–Sagittarius Arm
There are at least two smaller arms or spurs, including:
orange Orion–Cygnus Arm (which contains the Sun and Solar System)

Spitzer reveals what cannot be seen in visible light: cooler stars (blue), heated dust (reddish hue), and Sgr A* as bright white spot in the middle.

Artist’s conception of the spiral structure of the Milky Way with two major stellar arms and a bar.[196]

Two spiral arms, the Scutum–Centaurus arm and the Carina–Sagittarius arm, have tangent points inside the Sun’s orbit about the center of the Milky Way. If these arms contain an overdensity of stars compared to the average density of stars in the Galactic disk, it would be detectable by counting the stars near the tangent point. Two surveys of near-infrared light, which is sensitive primarily to red giants and not affected by dust extinction, detected the predicted overabundance in the Scutum–Centaurus arm but not in the Carina–Sagittarius arm: the Scutum–Centaurus Arm contains approximately 30% more red giants than would be expected in the absence of a spiral arm.[199][202] This observation suggests that the Milky Way possesses only two major stellar arms: the Perseus arm and the Scutum–Centaurus arm. The rest of the arms contain excess gas but not excess old stars.[196] In December 2013, astronomers found that the distribution of young stars and star-forming regions matches the four-arm spiral description of the Milky Way.[203][204][205] Thus, the Milky Way appears to have two spiral arms as traced by old stars and four spiral arms as traced by gas and young stars. The explanation for this apparent discrepancy is unclear.[205]

Clusters detected by WISE used to trace the Milky Way’s spiral arms.

The Near 3 kpc Arm (also called the Expanding 3 kpc Arm or simply the 3 kpc Arm) was discovered in the 1950s by astronomer van Woerden and collaborators through 21 centimeter radio measurements of HI (atomic hydrogen).[206][207] It was found to be expanding away from the central bulge at more than 50 km/s. It is located in the fourth galactic quadrant at a distance of about 5.2 kpc from the Sun and 3.3 kpc from the Galactic Center. The Far 3 kpc Arm was discovered in 2008 by astronomer Tom Dame (Center for Astrophysics | Harvard & Smithsonian). It is located in the first galactic quadrant at a distance of 3 kpc (about 10,000 ly) from the Galactic Center.[207][208]

A simulation published in 2011 suggested that the Milky Way may have obtained its spiral arm structure as a result of repeated collisions with the Sagittarius Dwarf Elliptical Galaxy.[209]

It has been suggested that the Milky Way contains two different spiral patterns: an inner one, formed by the Sagittarius arm, that rotates fast and an outer one, formed by the Carina and Perseus arms, whose rotation velocity is slower and whose arms are tightly wound. In this scenario, suggested by numerical simulations of the dynamics of the different spiral arms, the outer pattern would form an outer pseudoring,[210] and the two patterns would be connected by the Cygnus arm.[211]

The long filamentary molecular cloud dubbed «Nessie» probably forms a dense «spine» of the Scutum–Centarus Arm

Outside of the major spiral arms is the Monoceros Ring (or Outer Ring), a ring of gas and stars torn from other galaxies billions of years ago. However, several members of the scientific community recently restated their position affirming the Monoceros structure is nothing more than an over-density produced by the flared and warped thick disk of the Milky Way.[212] The structure of the Milky Way’s disk is warped along an «S» curve.[213]

Halo[edit]

The Galactic disk is surrounded by a spheroidal halo of old stars and globular clusters, of which 90% lie within 100,000 light-years (30 kpc) of the Galactic Center.[214] However, a few globular clusters have been found farther, such as PAL 4 and AM 1 at more than 200,000 light-years from the Galactic Center. About 40% of the Milky Way’s clusters are on retrograde orbits, which means they move in the opposite direction from the Milky Way rotation.[215] The globular clusters can follow rosette orbits about the Milky Way, in contrast to the elliptical orbit of a planet around a star.[216]

Although the disk contains dust that obscures the view in some wavelengths, the halo component does not. Active star formation takes place in the disk (especially in the spiral arms, which represent areas of high density), but does not take place in the halo, as there is little cool gas to collapse into stars.[101] Open clusters are also located primarily in the disk.[217]

Discoveries in the early 21st century have added dimension to the knowledge of the Milky Way’s structure. With the discovery that the disk of the Andromeda Galaxy (M31) extends much farther than previously thought,[218] the possibility of the disk of the Milky Way extending farther is apparent, and this is supported by evidence from the discovery of the Outer Arm extension of the Cygnus Arm[201][219] and of a similar extension of the Scutum–Centaurus Arm.[220] With the discovery of the Sagittarius Dwarf Elliptical Galaxy came the discovery of a ribbon of galactic debris as the polar orbit of the dwarf and its interaction with the Milky Way tears it apart. Similarly, with the discovery of the Canis Major Dwarf Galaxy, it was found that a ring of galactic debris from its interaction with the Milky Way encircles the Galactic disk.[citation needed]

The Sloan Digital Sky Survey of the northern sky shows a huge and diffuse structure (spread out across an area around 5,000 times the size of a full moon) within the Milky Way that does not seem to fit within current models. The collection of stars rises close to perpendicular to the plane of the spiral arms of the Milky Way. The proposed likely interpretation is that a dwarf galaxy is merging with the Milky Way. This galaxy is tentatively named the Virgo Stellar Stream and is found in the direction of Virgo about 30,000 light-years (9 kpc) away.[221]

Gaseous halo[edit]

In addition to the stellar halo, the Chandra X-ray Observatory, XMM-Newton, and Suzaku have provided evidence that there is a gaseous halo with a large amount of hot gas. The halo extends for hundreds of thousand of light-years, much farther than the stellar halo and close to the distance of the Large and Small Magellanic Clouds. The mass of this hot halo is nearly equivalent to the mass of the Milky Way itself.[222][223][224] The temperature of this halo gas is between 1 and 2.5 million K (1.8 and 4.5 million °F).[225]

Observations of distant galaxies indicate that the Universe had about one-sixth as much baryonic (ordinary) matter as dark matter when it was just a few billion years old. However, only about half of those baryons are accounted for in the modern Universe based on observations of nearby galaxies like the Milky Way.[226] If the finding that the mass of the halo is comparable to the mass of the Milky Way is confirmed, it could be the identity of the missing baryons around the Milky Way.[226]

Galactic rotation[edit]

Galaxy rotation curve for the Milky Way – vertical axis is speed of rotation about the galactic center; horizontal axis is distance from the galactic center in kpcs; the sun is marked with a yellow ball; the observed curve of speed of rotation is blue; the predicted curve based upon stellar mass and gas in the Milky Way is red; scatter in observations roughly indicated by gray bars, the difference is due to dark matter[36][227][228]

The stars and gas in the Milky Way rotate about its center differentially, meaning that the rotation period varies with location. As is typical for spiral galaxies, the orbital speed of most stars in the Milky Way does not depend strongly on their distance from the center. Away from the central bulge or outer rim, the typical stellar orbital speed is between 210 ± 10 km/s (470,000 ± 22,000 mph).[229] Hence the orbital period of the typical star is directly proportional only to the length of the path traveled. This is unlike the situation within the Solar System, where two-body gravitational dynamics dominate, and different orbits have significantly different velocities associated with them. The rotation curve (shown in the figure) describes this rotation. Toward the center of the Milky Way the orbit speeds are too low, whereas beyond 7 kpcs the speeds are too high to match what would be expected from the universal law of gravitation.[citation needed]

If the Milky Way contained only the mass observed in stars, gas, and other baryonic (ordinary) matter, the rotational speed would decrease with distance from the center. However, the observed curve is relatively flat, indicating that there is additional mass that cannot be detected directly with electromagnetic radiation. This inconsistency is attributed to dark matter.[36] The rotation curve of the Milky Way agrees with the universal rotation curve of spiral galaxies, the best evidence for the existence of dark matter in galaxies. Alternatively, a minority of astronomers propose that a modification of the law of gravity may explain the observed rotation curve.[230]

Formation[edit]

History[edit]

The Milky Way began as one or several small overdensities in the mass distribution in the Universe shortly after the Big Bang 13.61 billion years ago.[231][232][233] Some of these overdensities were the seeds of globular clusters in which the oldest remaining stars in what is now the Milky Way formed. Nearly half the matter in the Milky Way may have come from other distant galaxies.[231] Nonetheless, these stars and clusters now comprise the stellar halo of the Milky Way. Within a few billion years of the birth of the first stars, the mass of the Milky Way was large enough so that it was spinning relatively quickly. Due to conservation of angular momentum, this led the gaseous interstellar medium to collapse from a roughly spheroidal shape to a disk. Therefore, later generations of stars formed in this spiral disk. Most younger stars, including the Sun, are observed to be in the disk.[234][235]

Since the first stars began to form, the Milky Way has grown through both galaxy mergers (particularly early in the Milky Way’s growth) and accretion of gas directly from the Galactic halo.[235] The Milky Way is currently accreting material from several small galaxies, including two of its largest satellite galaxies, the Large and Small Magellanic Clouds, through the Magellanic Stream. Direct accretion of gas is observed in high-velocity clouds like the Smith Cloud.[236][237] Cosmological simulations indicate that, 11 billion years ago, it merged with a particularly large galaxy that has been labeled the Kraken.[238][239] However, properties of the Milky Way such as stellar mass, angular momentum, and metallicity in its outermost regions suggest it has undergone no mergers with large galaxies in the last 10 billion years. This lack of recent major mergers is unusual among similar spiral galaxies; its neighbour the Andromeda Galaxy appears to have a more typical history shaped by more recent mergers with relatively large galaxies.[240][241]

According to recent studies, the Milky Way as well as the Andromeda Galaxy lie in what in the galaxy color–magnitude diagram is known as the «green valley», a region populated by galaxies in transition from the «blue cloud» (galaxies actively forming new stars) to the «red sequence» (galaxies that lack star formation). Star-formation activity in green valley galaxies is slowing as they run out of star-forming gas in the interstellar medium. In simulated galaxies with similar properties, star formation will typically have been extinguished within about five billion years from now, even accounting for the expected, short-term increase in the rate of star formation due to the collision between both the Milky Way and the Andromeda Galaxy.[242] In fact, measurements of other galaxies similar to the Milky Way suggest it is among the reddest and brightest spiral galaxies that are still forming new stars and it is just slightly bluer than the bluest red sequence galaxies.[243]

Age and cosmological history[edit]

Comparison of the night sky with the night sky of a hypothetical planet within the Milky Way 10 billion years ago, at an age of about 3.6 billion years and 5 billion years before the Sun formed.[244]

Globular clusters are among the oldest objects in the Milky Way, which thus set a lower limit on the age of the Milky Way. The ages of individual stars in the Milky Way can be estimated by measuring the abundance of long-lived radioactive elements such as thorium-232 and uranium-238, then comparing the results to estimates of their original abundance, a technique called nucleocosmochronology. These yield values of about 12.5 ± 3 billion years for CS 31082-001[245] and 13.8 ± 4 billion years for BD +17° 3248.[246] Once a white dwarf is formed, it begins to undergo radiative cooling and the surface temperature steadily drops. By measuring the temperatures of the coolest of these white dwarfs and comparing them to their expected initial temperature, an age estimate can be made. With this technique, the age of the globular cluster M4 was estimated as 12.7 ± 0.7 billion years. Age estimates of the oldest of these clusters gives a best fit estimate of 12.6 billion years, and a 95% confidence upper limit of 16 billion years.[247]

In November 2018, astronomers reported the discovery of one of the oldest stars in the universe. About 13.5 billion-years-old, 2MASS J18082002-5104378 B is a tiny ultra metal-poor (UMP) star made almost entirely of materials released from the Big Bang, and is possibly one of the first stars. The discovery of the star in the Milky Way galaxy suggests that the galaxy may be at least 3 billion years older than previously thought.[248][249][250]

Several individual stars have been found in the Milky Way’s halo with measured ages very close to the 13.80-billion-year age of the Universe. In 2007, a star in the galactic halo, HE 1523-0901, was estimated to be about 13.2 billion years old. As the oldest known object in the Milky Way at that time, this measurement placed a lower limit on the age of the Milky Way.[251] This estimate was made using the UV-Visual Echelle Spectrograph of the Very Large Telescope to measure the relative strengths of spectral lines caused by the presence of thorium and other elements created by the R-process. The line strengths yield abundances of different elemental isotopes, from which an estimate of the age of the star can be derived using nucleocosmochronology.[251] Another star, HD 140283, is 14.5 ± 0.7 billion years old.[37][252]

According to observations utilizing adaptive optics to correct for Earth’s atmospheric distortion, stars in the galaxy’s bulge date to about 12.8 billion years old.[253]

The age of stars in the galactic thin disk has also been estimated using nucleocosmochronology. Measurements of thin disk stars yield an estimate that the thin disk formed 8.8 ± 1.7 billion years ago. These measurements suggest there was a hiatus of almost 5 billion years between the formation of the galactic halo and the thin disk.[254] Recent analysis of the chemical signatures of thousands of stars suggests that stellar formation might have dropped by an order of magnitude at the time of disk formation, 10 to 8 billion years ago, when interstellar gas was too hot to form new stars at the same rate as before.[255]

The satellite galaxies surrounding the Milky way are not randomly distributed but seem to be the result of a break-up of some larger system producing a ring structure 500,000 light-years in diameter and 50,000 light-years wide.[256] Close encounters between galaxies, like that expected in 4 billion years with the Andromeda Galaxy rips off huge tails of gas, which, over time can coalesce to form dwarf galaxies in a ring at an arbitrary angle to the main disc.[257]

Intergalactic neighbourhood[edit]

Diagram of the galaxies in the Local Group relative to the Milky Way

The Milky Way and the Andromeda Galaxy are a binary system of giant spiral galaxies belonging to a group of 50 closely bound galaxies known as the Local Group, surrounded by a Local Void, itself being part of the Local Sheet[258] and in turn the Virgo Supercluster. Surrounding the Virgo Supercluster are a number of voids, devoid of many galaxies, the Microscopium Void to the «north», the Sculptor Void to the «left», the Boötes Void to the «right» and the Canes-Major Void to the «south». These voids change shape over time, creating filamentous structures of galaxies. The Virgo Supercluster, for instance, is being drawn towards the Great Attractor,[259] which in turn forms part of a greater structure, called Laniakea.[260]

Two smaller galaxies and a number of dwarf galaxies in the Local Group orbit the Milky Way. The largest of these is the Large Magellanic Cloud with a diameter of 32,200 light-years.[261] It has a close companion, the Small Magellanic Cloud. The Magellanic Stream is a stream of neutral hydrogen gas extending from these two small galaxies across 100° of the sky. The stream is thought to have been dragged from the Magellanic Clouds in tidal interactions with the Milky Way.[262] Some of the dwarf galaxies orbiting the Milky Way are Canis Major Dwarf (the closest), Sagittarius Dwarf Elliptical Galaxy, Ursa Minor Dwarf, Sculptor Dwarf, Sextans Dwarf, Fornax Dwarf, and Leo I Dwarf. The smallest dwarf galaxies of the Milky Way are only 500 light-years in diameter. These include Carina Dwarf, Draco Dwarf, and Leo II Dwarf. There may still be undetected dwarf galaxies that are dynamically bound to the Milky Way, which is supported by the detection of nine new satellites of the Milky Way in a relatively small patch of the night sky in 2015.[263] There are also some dwarf galaxies that have already been absorbed by the Milky Way, such as the progenitor of Omega Centauri.[264]

In 2014 researchers reported that most satellite galaxies of the Milky Way lie in a very large disk and orbit in the same direction.[265] This came as a surprise: according to standard cosmology, the satellite galaxies should form in dark matter halos, and they should be widely distributed and moving in random directions. This discrepancy is still not fully explained.[266]

In January 2006, researchers reported that the heretofore unexplained warp in the disk of the Milky Way has now been mapped and found to be a ripple or vibration set up by the Large and Small Magellanic Clouds as they orbit the Milky Way, causing vibrations when they pass through its edges. Previously, these two galaxies, at around 2% of the mass of the Milky Way, were considered too small to influence the Milky Way. However, in a computer model, the movement of these two galaxies creates a dark matter wake that amplifies their influence on the larger Milky Way.[267]

Current measurements suggest the Andromeda Galaxy is approaching us at 100 to 140 km/s (220,000 to 310,000 mph). In 4.3 billion years, there may be an Andromeda–Milky Way collision, depending on the importance of unknown lateral components to the galaxies’ relative motion. If they collide, the chance of individual stars colliding with each other is extremely low,[268] but instead the two galaxies will merge to form a single elliptical galaxy or perhaps a large disk galaxy[269] over the course of about six billion years.[270]

Velocity[edit]

Although special relativity states that there is no «preferred» inertial frame of reference in space with which to compare the Milky Way, the Milky Way does have a velocity with respect to cosmological frames of reference.

One such frame of reference is the Hubble flow, the apparent motions of galaxy clusters due to the expansion of space. Individual galaxies, including the Milky Way, have peculiar velocities relative to the average flow. Thus, to compare the Milky Way to the Hubble flow, one must consider a volume large enough so that the expansion of the Universe dominates over local, random motions. A large enough volume means that the mean motion of galaxies within this volume is equal to the Hubble flow. Astronomers believe the Milky Way is moving at approximately 630 km/s (1,400,000 mph) with respect to this local co-moving frame of reference.[271][272] The Milky Way is moving in the general direction of the Great Attractor and other galaxy clusters, including the Shapley Supercluster, behind it.[273] The Local Group (a cluster of gravitationally bound galaxies containing, among others, the Milky Way and the Andromeda Galaxy) is part of a supercluster called the Local Supercluster, centered near the Virgo Cluster: although they are moving away from each other at 967 km/s (2,160,000 mph) as part of the Hubble flow, this velocity is less than would be expected given the 16.8 million pc distance due to the gravitational attraction between the Local Group and the Virgo Cluster.[274]

Another reference frame is provided by the cosmic microwave background (CMB), in which the CMB temperature is least distorted by Doppler shift (zero dipole moment). The Milky Way is moving at 552 ± 6 km/s (1,235,000 ± 13,000 mph)[16] with respect to this frame, toward 10.5 right ascension, −24° declination (J2000 epoch, near the center of Hydra). This motion is observed by satellites such as the Cosmic Background Explorer (COBE) and the Wilkinson Microwave Anisotropy Probe (WMAP) as a dipole contribution to the CMB, as photons in equilibrium in the CMB frame get blue-shifted in the direction of the motion and red-shifted in the opposite direction.[16]

See also[edit]

  • Baade’s Window
  • Galactic astronomy
  • Galactic Center GeV excess
  • Oort constants

Notes[edit]

  1. ^ a b The distance towards its center (Sagittarius A*).
  2. ^ a b Some authors use the term Milky Way to refer exclusively to the band of light that the galaxy forms in the night sky, while the galaxy receives the full name Milky Way Galaxy. See for example Lausten et al.,[275] Pasachoff,[276] Jones,[277] van der Kruit,[278] and Hodge et al.[279]
  3. ^ See also Bortle Dark-Sky Scale.
  4. ^ The bright center of the galaxy is located in the constellation Sagittarius. From Sagittarius, the hazy band of white light appears to pass westward through the constellations of Scorpius, Ara, Norma, Triangulum Australe, Circinus, Centaurus, Musca, Crux, Carina, Vela, Puppis, Canis Major, Monoceros, Orion and Gemini, Taurus, to the galactic anticenter in Auriga. From there, it passes through Perseus, Andromeda, Cassiopeia, Cepheus and Lacerta, Cygnus, Vulpecula, Sagitta, Aquila, Ophiuchus, Scutum, and back to Sagittarius.
  5. ^ These estimates are very uncertain, as most non-star objects are difficult to detect; for example, black hole estimates range from ten million to one billion.[280][281]
  6. ^ Karachentsev et al. give a blue absolute magnitude of −20.8. Combined with a color index of 0.55 estimated here, an absolute visual magnitude of −21.35 (−20.8 − 0.55 = −21.35) is obtained. Note that determining the absolute magnitude of the Milky Way is very difficult, because Earth is inside it.
  7. ^ For a photo see: «Sagittarius A*: Milky Way monster stars in cosmic reality show». Chandra X-ray Observatory. Center for Astrophysics | Harvard & Smithsonian. January 6, 2003. Archived from the original on March 17, 2008. Retrieved May 20, 2012.

Cite error: A list-defined reference has no name (see the help page).

Cite error: A list-defined reference has no name (see the help page).

References[edit]

  1. ^ a b Petrov, L.; Kovalev, Y. Y.; Fomalont, E. B.; Gordon, D. (2011). «The Very Long Baseline Array Galactic Plane Survey—VGaPS». The Astronomical Journal. 142 (2): 35. arXiv:1101.1460. Bibcode:2011AJ….142…35P. doi:10.1088/0004-6256/142/2/35. S2CID 121762178.
  2. ^ Event Horizon Telescope Collaboration; et al. (2022). «First Sagittarius A* Event Horizon Telescope Results. VI. Testing the Black Hole Metric». The Astrophysical Journal. 930 (2): L17. Bibcode:2022ApJ…930L..17E. doi:10.3847/2041-8213/ac6756. S2CID 248744741.
  3. ^ Banerjee, Indrani; Sau, Subhadip; SenGupta, Soumitra (2022). «Do shadows of SGR A* and M87* indicate black holes with a magnetic monopole charge?». arXiv:2207.06034 [gr-qc].
  4. ^ Abuter, R.; et al. (2019). «A geometric distance measurement to the Galactic center black hole with 0.3% uncertainty». Astronomy & Astrophysics. 625: L10. arXiv:1904.05721. Bibcode:2019A&A…625L..10G. doi:10.1051/0004-6361/201935656. S2CID 119190574.
  5. ^ a b Gerhard, O. (2002). «Mass distribution in our Galaxy». Space Science Reviews. 100 (1/4): 129–138. arXiv:astro-ph/0203110. Bibcode:2002SSRv..100..129G. doi:10.1023/A:1015818111633. S2CID 42162871.
  6. ^ Frommert, Hartmut; Kronberg, Christine (August 26, 2005). «Classification of the Milky Way Galaxy». SEDS. Archived from the original on May 31, 2015. Retrieved May 30, 2015.
  7. ^ Carlesi, Edoardo; Hoffman, Yehuda; Libeskind, Noam I. (2022). «Estimation of the masses in the local group by gradient boosted decision trees». Monthly Notices of the Royal Astronomical Society. 513 (2): 2385–2393. arXiv:2204.03334. doi:10.1093/mnras/stac897.
  8. ^ a b c d e Goodwin, S. P.; Gribbin, J.; Hendry, M. A. (August 1998). «The relative size of the Milky Way». The Observatory. 118: 201–208. Bibcode:1998Obs…118..201G.
  9. ^ a b Frommert, H.; Kronberg, C. (August 25, 2005). «The Milky Way Galaxy». SEDS. Archived from the original on May 12, 2007. Retrieved May 9, 2007.
  10. ^ a b Wethington, Nicholos. «How Many Stars are in the Milky Way?». Archived from the original on March 27, 2010. Retrieved April 9, 2010.
  11. ^ a b Bland-Hawthorn, Joss; Gerhard, Ortwin (2016). «The Galaxy in Context: Structural, Kinematic, and Integrated Properties». Annual Review of Astronomy and Astrophysics. 54: 529–596. arXiv:1602.07702. Bibcode:2016ARA&A..54..529B. doi:10.1146/annurev-astro-081915-023441. S2CID 53649594.
  12. ^ Karachentsev, Igor. «Double Galaxies § 7.1». ned.ipac.caltech.edu. Izdatel’stvo Nauka. Archived from the original on March 4, 2016. Retrieved April 5, 2015.
  13. ^ a b «A New Map of the Milky Way». Scientific American. April 1, 2020.
  14. ^ Gerhard, O. (2010). «Pattern speeds in the Milky Way». arXiv:1003.2489v1.
  15. ^ Shen, Juntai; Zheng, Xing-Wu (2020). «The bar and spiral arms in the Milky Way: Structure and kinematics». Research in Astronomy and Astrophysics. 20 (10): 159. arXiv:2012.10130. Bibcode:2020RAA….20..159S. doi:10.1088/1674-4527/20/10/159. S2CID 229005996.
  16. ^ a b c Kogut, Alan; et al. (December 10, 1993). «Dipole anisotropy in the COBE differential microwave radiometers first-year sky maps». The Astrophysical Journal. 419: 1…6. arXiv:astro-ph/9312056. Bibcode:1993ApJ…419….1K. doi:10.1086/173453. S2CID 209835274.
  17. ^ a b Kafle, P.R.; Sharma, S.; Lewis, G.F.; Bland-Hawthorn, J. (2014). «On the Shoulders of Giants: Properties of the Stellar Halo and the Milky Way Mass Distribution». The Astrophysical Journal. 794 (1): 17. arXiv:1408.1787. Bibcode:2014ApJ…794…59K. doi:10.1088/0004-637X/794/1/59. S2CID 119040135.
  18. ^ a b Harper, Douglas. «galaxy». Online Etymology Dictionary. Archived from the original on May 27, 2012. Retrieved May 20, 2012.
  19. ^ Jankowski, Connie (2010). Pioneers of Light and Sound. Compass Point Books. p. 6. ISBN 978-0-7565-4306-8. Archived from the original on November 20, 2016.
  20. ^ Schiller, Jon (2010). Big Bang & Black Holes. CreateSpace. p. 163. ISBN 978-1-4528-6552-2. Archived from the original on November 20, 2016.
  21. ^ «Milky Way Galaxy: Facts About Our Galactic Home». Space.com. Archived from the original on March 21, 2017. Retrieved April 8, 2017.
  22. ^ Shapley, H.; Curtis, H. D. (1921). «The Scale of the Universe». Bulletin of the National Research Council. 2 (11): 171–217. Bibcode:1921BuNRC…2..171S.
  23. ^ a b Croswell, Ken (March 23, 2020). «Astronomers have found the edge of the Milky Way at last». ScienceNews. Archived from the original on March 24, 2020. Retrieved March 27, 2020.
  24. ^ a b Dearson, Alis J. (2020). «The Edge of the Galaxy». Monthly Notices of the Royal Astronomical Society. 496 (3): 3929–3942. arXiv:2002.09497. Bibcode:2020MNRAS.496.3929D. doi:10.1093/mnras/staa1711. S2CID 211259409.
  25. ^ «Laniakea: Our home supercluster». youtube.com. Archived from the original on September 4, 2014.
  26. ^ Tully, R. Brent; et al. (September 4, 2014). «The Laniakea supercluster of galaxies». Nature. 513 (7516): 71–73. arXiv:1409.0880. Bibcode:2014Natur.513…71T. doi:10.1038/nature13674. PMID 25186900. S2CID 205240232.
  27. ^ «Milky Way». BBC. Archived from the original on March 2, 2012.
  28. ^ «How Many Stars in the Milky Way?». NASA Blueshift. Archived from the original on January 25, 2016.
  29. ^ a b c Cassan, A.; et al. (January 11, 2012). «One or more bound planets per Milky Way star from microlensing observations». Nature. 481 (7380): 167–169. arXiv:1202.0903. Bibcode:2012Natur.481..167C. doi:10.1038/nature10684. PMID 22237108. S2CID 2614136.
  30. ^ a b Staff (January 2, 2013). «100 Billion Alien Planets Fill Our Milky Way Galaxy: Study». Space.com. Archived from the original on January 3, 2013. Retrieved January 3, 2013.
  31. ^ a b c Gillessen, Stefan; Plewa, Philipp; Eisenhauer, Frank; Sari, Re’em; Waisberg, Idel; Habibi, Maryam; Pfuhl, Oliver; George, Elizabeth; Dexter, Jason; von Fellenberg, Sebastiano; Ott, Thomas; Genzel, Reinhard (November 28, 2016). «An Update on Monitoring Stellar Orbits in the Galactic Center». The Astrophysical Journal. 837 (1): 30. arXiv:1611.09144. Bibcode:2017ApJ…837…30G. doi:10.3847/1538-4357/aa5c41. S2CID 119087402.
  32. ^ Overbye, Dennis (January 31, 2022). «An Electrifying View of the Heart of the Milky Way – A new radio-wave image of the center of our galaxy reveals all the forms of frenzy that a hundred million or so stars can get up to». The New York Times. Archived from the original on January 31, 2022. Retrieved February 1, 2022.
  33. ^ Heyood, I.; et al. (January 28, 2022). «The 1.28 GHz MeerKAT Galactic Center Mosaic». The Astrophysical Journal. 925 (2): 165. arXiv:2201.10541. Bibcode:2022ApJ…925..165H. doi:10.3847/1538-4357/ac449a. S2CID 246275657.
  34. ^ a b c Starr, Michelle (March 8, 2019). «The Latest Calculation of Milky Way’s Mass Just Changed What We Know About Our Galaxy». ScienceAlert.com. Archived from the original on March 8, 2019. Retrieved March 8, 2019.
  35. ^ a b c Watkins, Laura L.; et al. (February 2, 2019). «Evidence for an Intermediate-Mass Milky Way from Gaia DR2 Halo Globular Cluster Motions». The Astrophysical Journal. 873 (2): 118. arXiv:1804.11348. Bibcode:2019ApJ…873..118W. doi:10.3847/1538-4357/ab089f. S2CID 85463973.
  36. ^ a b c Koupelis, Theo; Kuhn, Karl F. (2007). In Quest of the Universe. Jones & Bartlett Publishers. p. 492, Fig. 16–13. ISBN 978-0-7637-4387-1.
  37. ^ a b H.E. Bond; E. P. Nelan; D. A. VandenBerg; G. H. Schaefer; et al. (February 13, 2013). «HD 140283: A Star in the Solar Neighborhood that Formed Shortly After the Big Bang». The Astrophysical Journal. 765 (1): L12. arXiv:1302.3180. Bibcode:2013ApJ…765L..12B. doi:10.1088/2041-8205/765/1/L12. S2CID 119247629.
  38. ^ Brown, William P. (2010). The Seven Pillars of Creation: The Bible, Science, and the Ecology of Wonder. Oxford, England: Oxford University Press. p. 25. ISBN 978-0-19-973079-7.
  39. ^ MacBeath, Alastair (1999). Tiamat’s Brood: An Investigation Into the Dragons of Ancient Mesopotamia. Dragon’s Head. p. 41. ISBN 978-0-9524387-5-5.
  40. ^ James, E. O. (1963). The Worship of the Sky-God: A Comparative Study in Semitic and Indo-European Religion. Jordan Lectures in Comparative Religion. London, England: University of London Press. pp. 24, 27f.
  41. ^ a b Lambert, W. G. (1964). «E. O. James: The worship of the Skygod: A comparative study in Semitic and Indo-European religion. (School of Oriental and African Studies, University of London. Jordan Lectures in Comparative Religion, vi.) viii, 175 pp. London: University of London, the Athlone Press, 1963. 25s». Bulletin of the School of Oriental and African Studies. London, England: University of London. 27 (1): 157–158. doi:10.1017/S0041977X00100345.
  42. ^ «Myths about the Milky Way». judy-volker.com. Retrieved March 21, 2022.
  43. ^ Leeming, David Adams (1998). Mythology: The Voyage of the Hero (Third ed.). Oxford, England: Oxford University Press. p. 44. ISBN 978-0-19-511957-2.
  44. ^ Pache, Corinne Ondine (2010). «Hercules». In Gargarin, Michael; Fantham, Elaine (eds.). Ancient Greece and Rome. Vol. 1: Academy-Bible. Oxford, England: Oxford University Press. p. 400. ISBN 978-0-19-538839-8.
  45. ^ Keith, W. J. (July 2007). «John Cowper Powys: Owen Glendower» (PDF). A Reader’s Companion. Archived (PDF) from the original on May 14, 2016. Retrieved October 11, 2019.
  46. ^ Harvey, Michael (2018). «Dreaming the Night Field: A Scenario for Storytelling Performance». Storytelling, Self, Society. 14 (1): 83–94. doi:10.13110/storselfsoci.14.1.0083. ISSN 1550-5340.
  47. ^ «Eryri — Snowdonia». snowdonia-npa.gov.uk. Retrieved May 5, 2022.
  48. ^ Harris, Mike (2011). Awen: The Quest of the Celtic Mysteries. Skylight Press. p. 144. ISBN 978-1-908011-36-7. The stars of the Corona Borealis, the Caer Arianrhod, as it is called in Welsh, whose shape is remembered in certain Bronze Age circles
  49. ^ Jankowski, Connie (2010). Pioneers of Light and Sound. Compass Point Books. p. 6. ISBN 978-0-7565-4306-8. Archived from the original on November 20, 2016.
  50. ^ Schiller, Jon (2010). Big Bang & Black Holes. CreateSpace. p. 163. ISBN 978-1-4528-6552-2. Archived from the original on November 20, 2016.
  51. ^ Simpson, John; Weiner, Edmund, eds. (March 30, 1989). The Oxford English Dictionary (2nd ed.). Oxford University Press. ISBN 978-0-19-861186-8. See the entries for «Milky Way» and «galaxy».
  52. ^ Eratosthenes (1997). Condos, Theony (ed.). Star Myths of the Greeks and Romans: A Sourcebook Containing the Constellations of Pseudo-Eratosthenes and the Poetic Astronomy of Hyginus. Red Wheel/Weiser. ISBN 978-1-890482-93-0. Archived from the original on November 20, 2016.
  53. ^ Pasachoff, Jay M. (1994). Astronomy: From the Earth to the Universe. Harcourt School. p. 500. ISBN 978-0-03-001667-7.
  54. ^ Rey, H. A. (1976). The Stars. Houghton Mifflin Harcourt. p. 145. ISBN 978-0-395-24830-0.
  55. ^ Pasachoff, Jay M.; Filippenko, Alex (2013). The Cosmos: Astronomy in the New Millennium. Cambridge University Press. p. 384. ISBN 978-1-107-68756-1.
  56. ^ Crossen, Craig (July 2013). «Observing the Milky Way, part I: Sagittarius & Scorpius». Sky & Telescope. 126 (1): 24. Bibcode:2013S&T…126a..24C.
  57. ^ Urton, Gary (1981). At the Crossroads of the Earth and the Sky: An Andean Cosmology. Latin American Monographs. Vol. 55. Austin: Univ. of Texas Pr. pp. 102–4, 109–11. ISBN 0-292-70349-X.
  58. ^ Starr, Michelle (July 14, 2020). «A Giant ‘Wall’ of Galaxies Has Been Found Stretching Across The Universe». ScienceAlert. Retrieved May 5, 2022.
  59. ^ Crumey, Andrew (2014). «Human contrast threshold and astronomical visibility». Monthly Notices of the Royal Astronomical Society. 442 (3): 2600–2619. arXiv:1405.4209. Bibcode:2014MNRAS.442.2600C. doi:10.1093/mnras/stu992. S2CID 119210885.
  60. ^ Steinicke, Wolfgang; Jakiel, Richard (2007). Galaxies and how to observe them. Astronomers’ observing guides. Springer. p. 94. ISBN 978-1-85233-752-0.
  61. ^ Falchi, Fabio; Cinzano, Pierantonio; Duriscoe, Dan; Kyba, Christopher C. M.; Elvidge, Christopher D.; Baugh, Kimberly; Portnov, Boris A.; Rybnikova, Nataliya A.; Furgoni, Riccardo (June 1, 2016). «The new world atlas of artificial night sky brightness». Science Advances. 2 (6): e1600377. arXiv:1609.01041. Bibcode:2016SciA….2E0377F. doi:10.1126/sciadv.1600377. ISSN 2375-2548. PMC 4928945. PMID 27386582.
  62. ^ Aristotle with W. D. Ross, ed., The Works of Aristotle … (Oxford, England: Clarendon Press, 1931), vol. III, Meteorologica, E. W. Webster, trans., Book 1, Part 8, pp. 39–40 Archived April 11, 2016, at the Wayback Machine : «(2) Anaxagoras, Democritus, and their schools say that the milky way is the light of certain stars … shaded by the earth from the sun’s rays.»
  63. ^ a b «What does your image show». mo-www.harvard.edu. Retrieved October 20, 2022.
  64. ^ a b Montada, Josep Puig (September 28, 2007). «Ibn Bajja». Stanford Encyclopedia of Philosophy. Archived from the original on July 28, 2012. Retrieved July 11, 2008.
  65. ^ Aristotle; Ross, W. D. (William David); Smith, J. A. (John Alexander) (1908–52). Works. Translated into English under the editorship of W.D. Ross. Robarts — University of Toronto. Oxford Clarendon Press.{{cite book}}: CS1 maint: date format (link)
  66. ^ Heidarzadeh, Tofigh (2008). A history of physical theories of comets, from Aristotle to Whipple. Springer. pp. 23–25. ISBN 978-1-4020-8322-8.
  67. ^ O’Connor, John J.; Robertson, Edmund F., «Abu Rayhan Muhammad ibn Ahmad al-Biruni», MacTutor History of Mathematics archive, University of St Andrews[unreliable source?]
  68. ^ Ragep, Jamil (1993). Nasir al-Din al-Tusi’s Memoir on Astronomy (al-Tadhkira fi ‘ilm al-hay’ a). New York: Springer-Verlag. p. 129.
  69. ^ Livingston, John W. (1971). «Ibn Qayyim al-Jawziyyah: A Fourteenth Century Defense against Astrological Divination and Alchemical Transmutation». Journal of the American Oriental Society. 91 (1): 96–103 [99]. doi:10.2307/600445. JSTOR 600445.
  70. ^ Galileo Galilei, Sidereus Nuncius (Venice, (Italy): Thomas Baglioni, 1610), pages 15 and 16. Archived March 16, 2016, at the Wayback Machine
    English translation: Galileo Galilei with Edward Stafford Carlos, trans., The Sidereal Messenger (London: Rivingtons, 1880), pages 42 and 43. Archived December 2, 2012, at the Wayback Machine
  71. ^ O’Connor, J. J.; Robertson, E. F. (November 2002). «Galileo Galilei». University of St. Andrews. Archived from the original on May 30, 2012. Retrieved January 8, 2007.
  72. ^ Thomas Wright, An Original Theory or New Hypothesis of the Universe … (London, England: H. Chapelle, 1750).
    • On page 57 Archived November 20, 2016, at the Wayback Machine, Wright stated that despite their mutual gravitational attraction, the stars in the constellations don’t collide because they are in orbit, so centrifugal force keeps them separated: » … centrifugal force, which not only preserves them in their orbits, but prevents them from rushing all together, by the common universal law of gravity, … «
    • On page 48 Archived November 20, 2016, at the Wayback Machine, Wright stated that the form of the Milky Way is a ring: » … the stars are not infinitely dispersed and distributed in a promiscuous manner throughout all the mundane space, without order or design, … this phænomenon [is] no other than a certain effect arising from the observer’s situation, … To a spectator placed in an indefinite space, … it [i.e. the Milky Way (Via Lactea)] [is] a vast ring of stars … «
    • On page 65 Archived November 20, 2016, at the Wayback Machine, Wright speculated that the central body of the Milky Way, around which the rest of the galaxy revolves, might not be visible to us: » … the central body A, being supposed as incognitum [i.e. an unknown], without [i.e. outside of] the finite view; … «
    • On page 73 Archived November 20, 2016, at the Wayback Machine, Wright called the Milky Way the Vortex Magnus (the great whirlpool) and estimated its diameter to be 8.64×1012 miles (13.9×1012 km).
    • On page 33 Archived November 20, 2016, at the Wayback Machine, Wright speculated that there are a vast number of inhabited planets in the galaxy: » … ; therefore we may justly suppose, that so many radiant bodies [i.e. stars] were not created barely to enlighten an infinite void, but to … display an infinite shapeless universe, crowded with myriads of glorious worlds, all variously revolving round them; and … with an inconceivable variety of beings and states, animate … «

  73. ^ Immanuel Kant, Allgemeine Naturgeschichte und Theorie des Himmels … Archived November 20, 2016, at the Wayback Machine [Universal Natural History and Theory of Heaven … ], (Koenigsberg and Leipzig, (Germany): Johann Friederich Petersen, 1755).
    On pages 2–3, Kant acknowledged his debt to Thomas Wright: «Dem Herrn Wright von Durham, einen Engeländer, war es vorbehalten, einen glücklichen Schritt zu einer Bemerkung zu thun, welche von ihm selber zu keiner gar zu tüchtigen Absicht gebraucht zu seyn scheinet, und deren nützliche Anwendung er nicht genugsam beobachtet hat. Er betrachtete die Fixsterne nicht als ein ungeordnetes und ohne Absicht zerstreutes Gewimmel, sondern er fand eine systematische Verfassung im Ganzen, und eine allgemeine Beziehung dieser Gestirne gegen einen Hauptplan der Raume, die sie einnehmen.» (To Mr. Wright of Durham, an Englishman, it was reserved to take a happy step towards an observation, which seemed, to him and to no one else, to be needed for a clever idea, the exploitation of which he hasn’t studied sufficiently. He regarded the fixed stars not as a disorganized swarm that was scattered without a design; rather, he found a systematic shape in the whole, and a general relation between these stars and the principal plane of the space that they occupy.)
  74. ^ Kant (1755), pages xxxiii–xxxvi of the Preface (Vorrede): Archived November 20, 2016, at the Wayback Machine «Ich betrachtete die Art neblichter Sterne, deren Herr von Maupertuis in der Abhandlung von der Figur der Gestirne gedenket, und die die Figur von mehr oder weniger offenen Ellipsen vorstellen, und versicherte mich leicht, daß sie nichts anders als eine Häufung vieler Fixsterne seyn können. Die jederzeit abgemessene Rundung dieser Figuren belehrte mich, daß hier ein unbegreiflich zahlreiches Sternenheer, und zwar um einen gemeinschaftlichen Mittelpunkt, müste geordnet seyn, weil sonst ihre freye Stellungen gegen einander, wohl irreguläre Gestalten, aber nicht abgemessene Figuren vorstellen würden. Ich sahe auch ein: daß sie in dem System, darinn sie sich vereinigt befinden, vornemlich auf eine Fläche beschränkt seyn müßten, weil sie nicht zirkelrunde, sondern elliptische Figuren abbilden, und daß sie wegen ihres blassen Lichts unbegreiflich weit von uns abstehen.» (I considered the type of nebulous stars, which Mr. de Maupertuis considered in his treatise on the shape of stars, and which present the figures of more or less open ellipses, and I readily assured myself, that they could be nothing else than a cluster of fixed stars. That these figures always measured round informed me that here an inconceivably numerous host of stars, [which were clustered] around a common center, must be orderly, because otherwise their free positions among each other would probably present irregular forms, not measurable figures. I also realized: that in the system in which they find themselves bound, they must be restricted primarily to a plane, because they display not circular, but elliptical figures, and that on account of their faint light, they are located inconceivably far from us.)
  75. ^ Evans, J. C. (November 24, 1998). «Our Galaxy». George Mason University. Archived from the original on June 30, 2012. Retrieved January 4, 2007.
  76. ^ The term Weltinsel (island universe) appears nowhere in Kant’s book of 1755. The term first appeared in 1850, in the third volume of von Humboldt’s Kosmos: Alexander von Humboldt, Kosmos, vol. 3 (Stuttgart & Tübingen, (Germany): J.G. Cotta, 1850), pp. 187, 189. From p. 187: Archived November 20, 2016, at the Wayback Machine «Thomas Wright von Durham, Kant, Lambert und zuerst auch William Herschel waren geneigt die Gestalt der Milchstraße und die scheinbare Anhäufung der Sterne in derselben als eine Folge der abgeplatteten Gestalt und ungleichen Dimensionen der Weltinsel (Sternschict) zu betrachten, in welche unser Sonnensystem eingeschlossen ist.» (Thomas Wright of Durham, Kant, Lambert and first of all also William Herschel were inclined to regard the shape of the Milky Way and the apparent clustering of stars in it as a consequence of the oblate shape and unequal dimensions of the world island (star stratum), in which our solar system is included.)
    In the English translation – Alexander von Humboldt with E.C. Otté, trans., Cosmos … (New York City: Harper & Brothers, 1897), vols. 3–5. see p. 147 Archived November 6, 2018, at the Wayback Machine.
  77. ^ William Herschel (1785) «On the Construction of the Heavens,» Philosophical Transactions of the Royal Society of London, 75 : 213–266. Herschel’s diagram of the Milky Way appears immediately after the article’s last page. See:
    • Google Books Archived November 20, 2016, at the Wayback Machine
    • The Royal Society of London Archived April 6, 2016, at the Wayback Machine

  78. ^ Abbey, Lenny. «The Earl of Rosse and the Leviathan of Parsontown». The Compleat Amateur Astronomer. Archived from the original on May 19, 2013. Retrieved January 4, 2007.
  79. ^ See:
    • Rosse revealed the spiral structure of Whirlpool Galaxy (M51) at the 1845 meeting of the British Association for the Advancement of Science. Rosse’s illustration of M51 was reproduced in J.P. Nichol’s book of 1846.
    • Rosse, Earl of (1846). «On the nebula 25 Herschel, or 61 [should read: 51] of Messier’s catalogue». Report of the Fifteenth Meeting of the British Association for the Advancement of Science; Held at Cambridge in June 1845 § Notices and Abstracts of Miscellaneous Communications to the Sections. Report of the … Meeting of the British Association for the Advancement of Science (1833): 4.
    • Nichol, John Pringle (1846). Thoughts on Some Important Points Relating to the System of the World. Edinburgh, Scotland: William Tait. p. 23. Rosse’s illustration of the Whirlpool Galaxy appears on the plate that immediately precedes p. 23.
    • South, James (1846). «Auszug aus einem Berichte über Lord Rosse’s grosses Telescop, den Sir James South in The Times, Nr. 18899, 1845 April 16 bekannt gemacht hat» [Excerpt from a report about Lord Rosse’s great telescope, which Sir James South made known in The Times [of London], no. 18,899, 1845 April 16]. Astronomische Nachrichten. 23 (536): 113–118. doi:10.1002/asna.18460230802. On March 5, 1845, Rosse observed M51, the Whirlpool Galaxy. From column 115: «The most popularly known nebulæ observed this night were the ring nebulæ in the Canes Venatici, or the 51st of Messier’s catalogue, which was resolved into stars with a magnifying power of 548; … «
    • Robinson, T. R. (1845). «On Lord Rosse’s telescope». Proceedings of the Royal Irish Academy. 3 (50): 114–133. Rosse’s early observations of nebulae and galaxies are discussed on pp. 127–130.
    • Rosse, The Earl of (1850). «Observations on the nebulae». Philosophical Transactions of the Royal Society of London. 140: 499–514. doi:10.1098/rstl.1850.0026. Rosse’s illustrations of nebulae and galaxies appear on the plates that immediately precede the article.
    • Bailey, M. E.; Butler, C.J.; McFarland, J. (April 2005). «Unwinding the discovery of spiral nebulae». Astronomy & Geophysics. 46 (2): 2.26–2.28. doi:10.1111/j.1468-4004.2005.46226.x.

  80. ^ See:
    • Kapteyn, Jacobus Cornelius (1906). «Statistical methods in stellar astronomy». In Rogers, Howard J. (ed.). Congress of Arts and Science, Universal Exposition, St. Louis, 1904. Vol. 4. Boston and New York: Houghton, Mifflin and Co. pp. 396–425. From pp. 419–420: «It follows that the one set of the stars must have a systematic motion relative to the other. … these two main directions of motion must be in reality diametrically opposite.»
    • Kapteyn, J.C. (1905). «Star streaming». Report of the Seventy-fifth Meeting of the British Association for the Advancement of Science, South Africa. Report of the … Meeting of the British Association for the Advancement of Science (1833): 257–265.

  81. ^ See:
    • Schwarzschild, K. (1907). «Ueber die Eigenbewegungen der Fixsterne» [On the proper motions of the fixed stars]. Nachrichten von der Königlichen Gesellschaft der Wissenschaften zu Göttingen (Reports of the Royal Society of Science at Göttingen) (in German). 5: 614–632. Bibcode:1907NWGot…5..614S.
    • Schwarzschild, K. (1908). «Ueber die Bestimmung von Vertex und Apex nach der Ellipsoidhypothese aus einer geringeren Anzahl beobachteter Eigenbewegungen» [On the determination, according to the ellipsoid hypothesis, of the vertex and apex from a small number of observed proper motions]. Nachrichten von der Königlichen Gesellschaft der Wissenschaften zu Göttingen (in German): 191–200.

  82. ^ Curtis, Heber D. (1917). «Novae in spiral nebulae and the island universe theory». Publications of the Astronomical Society of the Pacific. 29 (171): 206–207. Bibcode:1917PASP…29..206C. doi:10.1086/122632.
  83. ^ Curtis, H. D. (1988). «Novae in spiral nebulae and the Island Universe Theory». Publications of the Astronomical Society of the Pacific. 100: 6–7. Bibcode:1988PASP..100….6C. doi:10.1086/132128.
  84. ^ Weaver, Harold F. «Robert Julius Trumpler». National Academy of Sciences. Archived from the original on June 4, 2012. Retrieved January 5, 2007.
  85. ^ Sandage, Allan (1989). «Edwin Hubble, 1889–1953». Journal of the Royal Astronomical Society of Canada. 83 (6): 351. Bibcode:1989JRASC..83..351S.
  86. ^ Hubble, E. P. (1929). «A spiral nebula as a stellar system, Messier 31». The Astrophysical Journal. 69: 103–158. Bibcode:1929ApJ….69..103H. doi:10.1086/143167.
  87. ^ «New Milky Way Map Is a Spectacular Billion-Star Atlas». September 14, 2016. Archived from the original on September 15, 2016. Retrieved September 15, 2016.
  88. ^ «Gaia > Gaia DR1». www.cosmos.esa.int. Archived from the original on September 15, 2016. Retrieved September 15, 2016.
  89. ^ Skibba, Ramin (June 10, 2021). «A galactic archaeologist digs into the Milky Way’s history». Knowable Magazine. doi:10.1146/knowable-060921-1. S2CID 236290725. Retrieved August 4, 2022.
  90. ^ Poggio, E.; Drimmel, R.; Andrae, R.; Bailer-Jones, C. A. L.; Fouesneau, M.; Lattanzi, M. G.; Smart, R. L.; Spagna, A. (2020). «Evidence of a dynamically evolving Galactic warp». Nature Astronomy. 4 (6): 590–596. arXiv:1912.10471. Bibcode:2020NatAs…4..590P. doi:10.1038/s41550-020-1017-3. S2CID 209444772.
  91. ^ a b Alves, João; Zucker, Catherine; Goodman, Alyssa A.; Speagle, Joshua S.; Meingast, Stefan; Robitaille, Thomas; Finkbeiner, Douglas P.; Schlafly, Edward F.; Green, Gregory M. (January 7, 2020). «A Galactic-scale gas wave in the Solar Neighborhood». Nature. 578 (7794): 237–239. arXiv:2001.08748. Bibcode:2020Natur.578..237A. doi:10.1038/s41586-019-1874-z. PMID 31910431. S2CID 210086520.
  92. ^ a b Boehle, A.; Ghez, A. M.; Schödel, R.; Meyer, L.; Yelda, S.; Albers, S.; Martinez, G. D.; Becklin, E. E.; Do, T.; Lu, J. R.; Matthews, K.; Morris, M. R.; Sitarski, B.; Witzel, G. (October 3, 2016). «An Improved Distance and Mass Estimate for SGR A* from a Multistar Orbit Analysis» (PDF). The Astrophysical Journal. 830 (1): 17. arXiv:1607.05726. Bibcode:2016ApJ…830…17B. doi:10.3847/0004-637X/830/1/17. hdl:10261/147803. S2CID 307657. Archived (PDF) from the original on December 2, 2017. Retrieved July 31, 2018.
  93. ^ Majaess, D. J.; Turner, D. G.; Lane, D. J. (2009). «Characteristics of the Galaxy according to Cepheids». Monthly Notices of the Royal Astronomical Society. 398 (1): 263–270. arXiv:0903.4206. Bibcode:2009MNRAS.398..263M. doi:10.1111/j.1365-2966.2009.15096.x. S2CID 14316644.
  94. ^ English, Jayanne (January 14, 2000). «Exposing the Stuff Between the Stars». Hubble News Desk. Archived from the original on July 7, 2007. Retrieved May 10, 2007.
  95. ^ Mullen, Leslie (May 18, 2001). «Galactic Habitable Zones». NAI Features Archive. Nasa Astrobiology Institute. Archived from the original on April 9, 2013. Retrieved May 9, 2013.
  96. ^ Sundin, M. (2006). «The galactic habitable zone in barred galaxies». International Journal of Astrobiology. 5 (4): 325–326. Bibcode:2006IJAsB…5..325S. doi:10.1017/S1473550406003065. S2CID 122018103.
  97. ^ «Magnitude». National Solar Observatory – Sacramento Peak. Archived from the original on February 6, 2008. Retrieved August 9, 2013.
  98. ^ Moore, Patrick; Rees, Robin (2014). Patrick Moore’s Data Book of Astronomy (2nd ed.). Cambridge University Press. p. 4. ISBN 978-1-139-49522-6. Archived from the original on February 15, 2017.
  99. ^ Gillman, M.; Erenler, H. (2008). «The galactic cycle of extinction» (PDF). International Journal of Astrobiology. 7 (1): 17. Bibcode:2008IJAsB…7…17G. CiteSeerX 10.1.1.384.9224. doi:10.1017/S1473550408004047. S2CID 31391193. Archived (PDF) from the original on June 1, 2019. Retrieved July 31, 2018.
  100. ^ Overholt, A. C.; Melott, A. L.; Pohl, M. (2009). «Testing the link between terrestrial climate change and galactic spiral arm transit». The Astrophysical Journal. 705 (2): L101–L103. arXiv:0906.2777. Bibcode:2009ApJ…705L.101O. doi:10.1088/0004-637X/705/2/L101. S2CID 734824.
  101. ^ a b Sparke, Linda S.; Gallagher, John S. (2007). Galaxies in the Universe: An Introduction. p. 90. ISBN 978-1-139-46238-9.
  102. ^ Garlick, Mark Antony (2002). The Story of the Solar System. Cambridge University. p. 46. ISBN 978-0-521-80336-6.
  103. ^ «Solar System’s ‘Nose’ Found; Aimed at Constellation Scorpius». April 8, 2011. Archived from the original on September 7, 2015.
  104. ^ Blaauw, A.; et al. (1960), «The new I. A. U. system of galactic coordinates (1958 revision)», Monthly Notices of the Royal Astronomical Society, 121 (2): 123–131, Bibcode:1960MNRAS.121..123B, doi:10.1093/mnras/121.2.123
  105. ^ a b Wilson, Thomas L.; et al. (2009), Tools of Radio Astronomy, Springer Science & Business Media, ISBN 978-3-540-85121-9, archived from the original on April 26, 2016
  106. ^ a b Kiss, Cs; Moór, A.; Tóth, L. V. (April 2004). «Far-infrared loops in the 2nd Galactic Quadrant». Astronomy and Astrophysics. 418: 131–141. arXiv:astro-ph/0401303. Bibcode:2004A&A…418..131K. doi:10.1051/0004-6361:20034530. S2CID 7825138.
  107. ^ a b Lampton, M., Lieu, R.; et al. (February 1997). «An All-Sky Catalog of Faint Extreme Ultraviolet Sources». The Astrophysical Journal Supplement Series. 108 (2): 545–557. Bibcode:1997ApJS..108..545L. doi:10.1086/312965.
  108. ^ van Woerden, Hugo; Strom, Richard G. (June 2006). «The beginnings of radio astronomy in the Netherlands» (PDF). Journal of Astronomical History and Heritage. 9 (1): 3–20. Bibcode:2006JAHH….9….3V. Archived from the original (PDF) on September 19, 2010.
  109. ^ a b c López-Corredoira, M.; Allende Prieto, C.; Garzón, F.; Wang, H.; Liu, C.; Deng, L. (April 9, 2018). «Disk stars in the Milky Way detected beyond 25 KPC from its center». Astronomy & Astrophysics. 612: L8. arXiv:1804.03064. Bibcode:2018A&A…612L…8L. doi:10.1051/0004-6361/201832880. S2CID 59933365.
  110. ^ a b Sale, S. E.; et al. (2010). «The structure of the outer Galactic disc as revealed by IPHAS early A stars». Monthly Notices of the Royal Astronomical Society. 402 (2): 713–723. arXiv:0909.3857. Bibcode:2010MNRAS.402..713S. doi:10.1111/j.1365-2966.2009.15746.x. S2CID 12884630.
  111. ^ https://ned.ipac.caltech.edu/level5/PROPERTIES/dog.html[bare URL]
  112. ^ Goodwin, S. P.; Gribbin, J.; Hendry, M. A. (April 22, 1997). «The Milky Way is just an average spiral». arXiv:astro-ph/9704216.
  113. ^ Castro-Rodríguez, N.; López-Corredoira, M.; Sánchez-Saavedra, M. L.; Battaner, E. (2002). «Warps and correlations with intrinsic parameters of galaxies in the visible and radio». Astronomy & Astrophysics. 391 (2): 519–530. arXiv:astro-ph/0205553. Bibcode:2002A&A…391..519C. doi:10.1051/0004-6361:20020895. S2CID 17813024.
  114. ^ Goodwin, S. P.; Gribbin, J.; Hendry, M. A. (April 30, 1997). «New Determination of the Hubble Parameter Using the Principle of Terrestrial Mediocrity». arXiv:astro-ph/9704289.
  115. ^ «How Big is Our Universe: How far is it across the Milky Way?». NASA-Smithsonian Education Forum on the Structure and Evolution of the Universe, at the Harvard Smithsonian Center for Astrophysics. Archived from the original on March 5, 2013. Retrieved March 13, 2013.
  116. ^ Newberg, Heidi Jo; et al. (March 1, 2015). «Rings and Radial Waves in the Disk of the Milky Way». The Astrophysical Journal. 801 (2): 105. arXiv:1503.00257. Bibcode:2015ApJ…801..105X. doi:10.1088/0004-637X/801/2/105. S2CID 119124338.
  117. ^ Mary L. Martialay (March 11, 2015). «The Corrugated Galaxy – Milky Way May Be Much Larger Than Previously Estimated» (Press release). Rensselaer Polytechnic Institute. Archived from the original on March 13, 2015.
  118. ^ Sheffield, Allyson A.; Price-Whelan, Adrian M.; Tzanidakis, Anastasios; Johnston, Kathryn V.; Laporte, Chervin F. P.; Sesar, Branimir (2018). «A Disk Origin for the Monoceros Ring and A13 Stellar Overdensities». The Astrophysical Journal. 854 (1): 47. arXiv:1801.01171. Bibcode:2018ApJ…854…47S. doi:10.3847/1538-4357/aaa4b6. S2CID 118932403.
  119. ^ David Freeman (May 25, 2018). «The Milky Way galaxy may be much bigger than we thought» (Press release). CNBC. Archived from the original on August 13, 2018. Retrieved August 13, 2018.
  120. ^ July 2018, Elizabeth Howell 02 (July 2, 2018). «It Would Take 200,000 Years at Light Speed to Cross the Milky Way». Space.com.
  121. ^ Coffey, Jeffrey. «How big is the Milky Way?». Universe Today. Archived from the original on September 24, 2013. Retrieved November 28, 2007.
  122. ^ Rix, Hans-Walter; Bovy, Jo (2013). «The Milky Way’s Stellar Disk». The Astronomy and Astrophysics Review. 21: 61. arXiv:1301.3168. Bibcode:2013A&ARv..21…61R. doi:10.1007/s00159-013-0061-8. S2CID 117112561.
  123. ^ Kafle, P.R.; Sharma, S.; Lewis, G.F.; Bland-Hawthorn, J. (2012). «Kinematics of the Stellar Halo and the Mass Distribution of the Milky Way Using Blue Horizontal Branch Stars». The Astrophysical Journal. 761 (2): 17. arXiv:1210.7527. Bibcode:2012ApJ…761…98K. doi:10.1088/0004-637X/761/2/98. S2CID 119303111.
  124. ^ Karachentsev, I. D.; Kashibadze, O. G. (2006). «Masses of the local group and of the M81 group estimated from distortions in the local velocity field». Astrophysics. 49 (1): 3–18. Bibcode:2006Ap…..49….3K. doi:10.1007/s10511-006-0002-6. S2CID 120973010.
  125. ^ Vayntrub, Alina (2000). «Mass of the Milky Way». The Physics Factbook. Archived from the original on August 13, 2014. Retrieved May 9, 2007.
  126. ^ Battaglia, G.; et al. (2005). «The radial velocity dispersion profile of the Galactic halo: Constraining the density profile of the dark halo of the Milky Way». Monthly Notices of the Royal Astronomical Society. 364 (2): 433–442. arXiv:astro-ph/0506102. Bibcode:2005MNRAS.364..433B. doi:10.1111/j.1365-2966.2005.09367.x. S2CID 15562509.
  127. ^ Finley, Dave; Aguilar, David (January 5, 2009). «Milky Way a Swifter Spinner, More Massive, New Measurements Show» (Press release). National Radio Astronomy Observatory. Archived from the original on August 8, 2014. Retrieved January 20, 2009.
  128. ^ Reid, M. J.; et al. (2009). «Trigonometric parallaxes of massive star-forming regions. VI. Galactic structure, fundamental parameters, and noncircular motions». The Astrophysical Journal. 700 (1): 137–148. arXiv:0902.3913. Bibcode:2009ApJ…700..137R. doi:10.1088/0004-637X/700/1/137. S2CID 11347166.
  129. ^ Gnedin, O. Y.; et al. (2010). «The mass profile of the Galaxy to 80 kpc». The Astrophysical Journal. 720 (1): L108–L112. arXiv:1005.2619. Bibcode:2010ApJ…720L.108G. doi:10.1088/2041-8205/720/1/L108. S2CID 119245657.
  130. ^ a b Peñarrubia, Jorge; et al. (2014). «A dynamical model of the local cosmic expansion». Monthly Notices of the Royal Astronomical Society. 433 (3): 2204–2222. arXiv:1405.0306. Bibcode:2014MNRAS.443.2204P. doi:10.1093/mnras/stu879. S2CID 119295582.
  131. ^ Grand, Robert J J.; Deason, Alis J.; White, Simon D M.; Simpson, Christine M.; Gómez, Facundo A.; Marinacci, Federico; Pakmor, Rüdiger (2019). «The effects of dynamical substructure on Milky Way mass estimates from the high-velocity tail of the local stellar halo». Monthly Notices of the Royal Astronomical Society: Letters. 487 (1): L72–L76. arXiv:1905.09834. Bibcode:2019MNRAS.487L..72G. doi:10.1093/mnrasl/slz092. S2CID 165163524.
  132. ^ a b McMillan, P. J. (July 2011). «Mass models of the Milky Way». Monthly Notices of the Royal Astronomical Society. 414 (3): 2446–2457. arXiv:1102.4340. Bibcode:2011MNRAS.414.2446M. doi:10.1111/j.1365-2966.2011.18564.x. S2CID 119100616.
  133. ^ McMillan, Paul J. (February 11, 2017). «The mass distribution and gravitational potential of the Milky Way». Monthly Notices of the Royal Astronomical Society. 465 (1): 76–94. arXiv:1608.00971. Bibcode:2017MNRAS.465…76M. doi:10.1093/mnras/stw2759. S2CID 119183093.
  134. ^ Slobodan Ninković (April 2017). «Mass Distribution and Gravitational Potential of the Milky Way». Open Astronomy. 26 (1): 1–6. Bibcode:2017OAst…26….1N. doi:10.1515/astro-2017-0002.
  135. ^ Phelps, Steven; et al. (October 2013). «The Mass of the Milky Way and M31 Using the Method of Least Action». The Astrophysical Journal. 775 (2): 102–113. arXiv:1306.4013. Bibcode:2013ApJ…775..102P. doi:10.1088/0004-637X/775/2/102. S2CID 21656852. 102.
  136. ^ Kafle, Prajwal Raj; et al. (October 2014). «On the Shoulders of Giants: Properties of the Stellar Halo and the Milky Way Mass Distribution». The Astrophysical Journal. 794 (1): 17. arXiv:1408.1787. Bibcode:2014ApJ…794…59K. doi:10.1088/0004-637X/794/1/59. S2CID 119040135. 59.
  137. ^ Licquia, Timothy; Newman, J. (2013). «Improved Constraints on the Total Stellar Mass, Color, and Luminosity of the Milky Way». American Astronomical Society, AAS Meeting #221, #254.11. 221: 254.11. Bibcode:2013AAS…22125411L.
  138. ^ a b c «The Interstellar Medium». Archived from the original on April 19, 2015. Retrieved May 2, 2015.
  139. ^ a b «Lecture Seven: The Milky Way: Gas» (PDF). Archived from the original (PDF) on July 8, 2015. Retrieved May 2, 2015.
  140. ^ Villard, Ray (January 11, 2012). «The Milky Way Contains at Least 100 Billion Planets According to Survey». HubbleSite.org. Archived from the original on July 23, 2014. Retrieved January 11, 2012.
  141. ^ Young, Kelly (June 6, 2006). «Andromeda Galaxy hosts a trillion stars». New Scientist. Archived from the original on January 5, 2011. Retrieved June 8, 2006.
  142. ^ Napiwotzki, R. (2009). The galactic population of white dwarfs. In Journal of Physics: Conference Series (Vol. 172, No. 1, p. 012004). IOP Publishing.
  143. ^ «NASA – Neutron Stars». NASA. Archived from the original on September 8, 2018. Retrieved April 5, 2018.
  144. ^ a b Levine, E. S.; Blitz, L.; Heiles, C. (2006). «The spiral structure of the outer Milky Way in hydrogen». Science. 312 (5781): 1773–1777. arXiv:astro-ph/0605728. Bibcode:2006Sci…312.1773L. doi:10.1126/science.1128455. PMID 16741076. S2CID 12763199.
  145. ^ Dickey, J. M.; Lockman, F. J. (1990). «H I in the Galaxy». Annual Review of Astronomy and Astrophysics. 28: 215–259. Bibcode:1990ARA&A..28..215D. doi:10.1146/annurev.aa.28.090190.001243.
  146. ^ Savage, B. D.; Wakker, B. P. (2009). «The extension of the transition temperature plasma into the lower galactic halo». The Astrophysical Journal. 702 (2): 1472–1489. arXiv:0907.4955. Bibcode:2009ApJ…702.1472S. doi:10.1088/0004-637X/702/2/1472. S2CID 119245570.
  147. ^ Connors, Tim W.; Kawata, Daisuke; Gibson, Brad K. (2006). «N-body simulations of the Magellanic stream». Monthly Notices of the Royal Astronomical Society. 371 (1): 108–120. arXiv:astro-ph/0508390. Bibcode:2006MNRAS.371..108C. doi:10.1111/j.1365-2966.2006.10659.x. S2CID 15563258.
  148. ^ Coffey, Jerry (May 11, 2017). «Absolute Magnitude». Archived from the original on September 13, 2011.
  149. ^ Karachentsev, Igor D.; Karachentseva, Valentina E.; Huchtmeier, Walter K.; Makarov, Dmitry I. (2003). «A Catalog of Neighboring Galaxies». The Astronomical Journal. 127 (4): 2031–2068. Bibcode:2004AJ….127.2031K. doi:10.1086/382905.
  150. ^ Borenstein, Seth (February 19, 2011). «Cosmic census finds crowd of planets in our galaxy». The Washington Post. Associated Press. Archived from the original on February 22, 2011.
  151. ^ Sumi, T.; et al. (2011). «Unbound or distant planetary mass population detected by gravitational microlensing». Nature. 473 (7347): 349–352. arXiv:1105.3544. Bibcode:2011Natur.473..349S. doi:10.1038/nature10092. PMID 21593867. S2CID 4422627.
  152. ^ «Free-Floating Planets May be More Common Than Stars». Pasadena, CA: NASA’s Jet Propulsion Laboratory. February 18, 2011. Archived from the original on May 22, 2011. The team estimates there are about twice as many of them as stars.
  153. ^ Staff (January 7, 2013). «17 Billion Earth-Size Alien Planets Inhabit Milky Way». Space.com. Archived from the original on October 6, 2014. Retrieved January 8, 2013.
  154. ^ Overbye, Dennis (November 4, 2013). «Far-Off Planets Like the Earth Dot the Galaxy». New York Times. Archived from the original on November 5, 2013. Retrieved November 5, 2013.
  155. ^ Petigura, Eric A.; Howard, Andrew W.; Marcy, Geoffrey W. (October 31, 2013). «Prevalence of Earth-size planets orbiting Sun-like stars». Proceedings of the National Academy of Sciences of the United States of America. 110 (48): 19273–19278. arXiv:1311.6806. Bibcode:2013PNAS..11019273P. doi:10.1073/pnas.1319909110. PMC 3845182. PMID 24191033.
  156. ^ Borenstein, Seth (November 4, 2013). «Milky Way Teeming With Billions Of Earth-Size Planets». The Associated Press. The Huffington Post. Archived from the original on November 4, 2014.
  157. ^ Khan, Amina (November 4, 2013). «Milky Way may host billions of Earth-size planets». Los Angeles Times. Archived from the original on November 6, 2013. Retrieved November 5, 2013.
  158. ^ Anglada-Escudé, Guillem; Amado, Pedro J.; Barnes, John; et al. (2016). «A terrestrial planet candidate in a temperate orbit around Proxima Centauri». Nature. 536 (7617): 437–440. arXiv:1609.03449. Bibcode:2016Natur.536..437A. doi:10.1038/nature19106. PMID 27558064. S2CID 4451513.
  159. ^ Staff (January 7, 2013). «‘Exocomets’ Common Across Milky Way Galaxy». Space.com. Archived from the original on September 16, 2014. Retrieved January 8, 2013.
  160. ^ Overbye, Dennis (November 5, 2020). «Looking for Another Earth? Here Are 300 Million, Maybe – A new analysis of data from NASA’s Kepler spacecraft increases the number of habitable exoplanets thought to exist in this galaxy». The New York Times. Archived from the original on November 5, 2020. Retrieved November 5, 2020.
  161. ^ a b Chou, Felicia; Anderson, Janet; Watzke, Megan (January 5, 2015). «Release 15-001 – NASA’s Chandra Detects Record-Breaking Outburst from Milky Way’s Black Hole». NASA. Archived from the original on January 6, 2015. Retrieved January 6, 2015.
  162. ^ «The Milky Way is warped». phys.org. Archived from the original on February 7, 2019. Retrieved February 22, 2019.
  163. ^ Chen, Xiaodian; Wang, Shu; Deng, Licai; de Grijs, Richard; Liu, Chao; Tian, Hao (February 4, 2019). «An intuitive 3D map of the Galactic warp’s precession traced by classical Cepheids». Nature Astronomy. 3 (4): 320–325. arXiv:1902.00998. Bibcode:2019NatAs…3..320C. doi:10.1038/s41550-018-0686-7. ISSN 2397-3366. S2CID 119290364.
  164. ^ Gerard de Vaucouleurs (1964), Interpretation of velocity distribution of the inner regions of the Galaxy Archived February 3, 2019, at the Wayback Machine
  165. ^ Peters, W.L. III. (1975), Models for the inner regions of the Galaxy. I Archived February 3, 2019, at the Wayback Machine
  166. ^ Hammersley, P. L.; Garzon, F.; Mahoney, T.; Calbet, X. (1994), Infrared Signatures of the Inner Spiral Arms and Bar Archived February 3, 2019, at the Wayback Machine
  167. ^ McKee, Maggie (August 16, 2005). «Bar at Milky Way’s heart revealed». New Scientist. Archived from the original on October 9, 2014. Retrieved June 17, 2009.
  168. ^ a b Gillessen, S.; et al. (2009). «Monitoring stellar orbits around the massive black hole in the Galactic Center». Astrophysical Journal. 692 (2): 1075–1109. arXiv:0810.4674. Bibcode:2009ApJ…692.1075G. doi:10.1088/0004-637X/692/2/1075. S2CID 1431308.
  169. ^ Reid, M. J.; et al. (November 2009). «A trigonometric parallax of Sgr B2». The Astrophysical Journal. 705 (2): 1548–1553. arXiv:0908.3637. Bibcode:2009ApJ…705.1548R. doi:10.1088/0004-637X/705/2/1548. S2CID 1916267.
  170. ^ a b Vanhollebeke, E.; Groenewegen, M. A. T.; Girardi, L. (April 2009). «Stellar populations in the Galactic bulge. Modelling the Galactic bulge with TRILEGAL». Astronomy and Astrophysics. 498 (1): 95–107. arXiv:0903.0946. Bibcode:2009A&A…498…95V. doi:10.1051/0004-6361/20078472.
  171. ^ a b c d Majaess, D. (March 2010). «Concerning the Distance to the Center of the Milky Way and Its Structure». Acta Astronomica. 60 (1): 55. arXiv:1002.2743. Bibcode:2010AcA….60…55M.
  172. ^ Grant, J.; Lin, B. (2000). «The Stars of the Milky Way». Fairfax Public Access Corporation. Archived from the original on June 11, 2007. Retrieved May 9, 2007.
  173. ^ Shen, J.; Rich, R. M.; Kormendy, J.; Howard, C. D.; De Propris, R.; Kunder, A. (2010). «Our Milky Way As a Pure-Disk Galaxy – A Challenge for Galaxy Formation». The Astrophysical Journal. 720 (1): L72–L76. arXiv:1005.0385. Bibcode:2010ApJ…720L..72S. doi:10.1088/2041-8205/720/1/L72. S2CID 118470423.
  174. ^ Ciambur, Bogdan C.; Graham, Alister W.; Bland-Hawthorn, Joss (2017). «Quantifying the (X/peanut)-shaped structure of the Milky Way – new constraints on the bar geometry». Monthly Notices of the Royal Astronomical Society. 471 (4): 3988. arXiv:1706.09902. Bibcode:2017MNRAS.471.3988C. doi:10.1093/mnras/stx1823. S2CID 119376558.
  175. ^ Jones, Mark H.; Lambourne, Robert J.; Adams, David John (2004). An Introduction to Galaxies and Cosmology. Cambridge University Press. pp. 50–51. ISBN 978-0-521-54623-2.
  176. ^ a b Ghez, A. M.; et al. (December 2008). «Measuring distance and properties of the Milky Way’s central supermassive black hole with stellar orbits». The Astrophysical Journal. 689 (2): 1044–1062. arXiv:0808.2870. Bibcode:2008ApJ…689.1044G. doi:10.1086/592738. S2CID 18335611.
  177. ^ a b Wang, Q.D.; Nowak, M.A.; Markoff, S.B.; Baganoff, F.K.; Nayakshin, S.; Yuan, F.; Cuadra, J.; Davis, J.; Dexter, J.; Fabian, A.C.; Grosso, N.; Haggard, D.; Houck, J.; Ji, L.; Li, Z.; Neilsen, J.; Porquet, D.; Ripple, F.; Shcherbakov, R.V. (2013). «Dissecting X-ray-Emitting Gas Around the Center of Our Galaxy». Science. 341 (6149): 981–983. arXiv:1307.5845. Bibcode:2013Sci…341..981W. doi:10.1126/science.1240755. PMID 23990554. S2CID 206550019.
  178. ^ Blandford, R. D. (August 8–12, 1998). Origin and Evolution of Massive Black Holes in Galactic Nuclei. Galaxy Dynamics, proceedings of a conference held at Rutgers University, ASP Conference Series. Vol. 182. Rutgers University (published August 1999). arXiv:astro-ph/9906025. Bibcode:1999ASPC..182…87B.
  179. ^ Frolov, Valeri P.; Zelnikov, Andrei (2011). Introduction to Black Hole Physics. Oxford University Press. pp. 11, 36. ISBN 978-0-19-969229-3. Archived from the original on August 10, 2016.
  180. ^ Cabrera-Lavers, A.; et al. (December 2008). «The long Galactic bar as seen by UKIDSS Galactic plane survey». Astronomy and Astrophysics. 491 (3): 781–787. arXiv:0809.3174. Bibcode:2008A&A…491..781C. doi:10.1051/0004-6361:200810720. S2CID 15040792.
  181. ^ Nishiyama, S.; et al. (2005). «A distinct structure inside the Galactic bar». The Astrophysical Journal. 621 (2): L105. arXiv:astro-ph/0502058. Bibcode:2005ApJ…621L.105N. doi:10.1086/429291. S2CID 399710.
  182. ^ Alcock, C.; et al. (1998). «The RR Lyrae population of the Galactic Bulge from the MACHO database: mean colors and magnitudes». The Astrophysical Journal. 492 (2): 190–199. Bibcode:1998ApJ…492..190A. doi:10.1086/305017.
  183. ^ Kunder, A.; Chaboyer, B. (2008). «Metallicity analysis of Macho Galactic Bulge RR0 Lyrae stars from their light curves». The Astronomical Journal. 136 (6): 2441–2452. arXiv:0809.1645. Bibcode:2008AJ….136.2441K. doi:10.1088/0004-6256/136/6/2441. S2CID 16046532.
  184. ^ Staff (September 12, 2005). «Introduction: Galactic Ring Survey». Boston University. Archived from the original on July 13, 2007. Retrieved May 10, 2007.
  185. ^ Bhat, C. L.; Kifune, T.; Wolfendale, A. W. (November 21, 1985). «A cosmic-ray explanation of the galactic ridge of cosmic X-rays». Nature. 318 (6043): 267–269. Bibcode:1985Natur.318..267B. doi:10.1038/318267a0. S2CID 4262045.
  186. ^ Georg Weidenspointner; et al. (January 10, 2008). «An asymmetric distribution of positrons in the Galactic disk revealed by γ-rays». Nature. 451 (7175): 159–162. Bibcode:2008Natur.451..159W. doi:10.1038/nature06490. PMID 18185581. S2CID 4333175.
  187. ^ a b «NASA – Satellite Explains Giant Cloud of Antimatter». www.nasa.gov. January 9, 2008. Retrieved July 2, 2021.
  188. ^ «Antimatter Clouds and Fountains – NASA Press Release 97-83». heasarc.gsfc.nasa.gov. Retrieved July 2, 2021.
  189. ^ Overbye, Dennis (November 9, 2010). «Bubbles of Energy Are Found in Galaxy». The New York Times. Archived from the original on January 10, 2016.
  190. ^ «NASA’s Fermi Telescope Finds Giant Structure in our Galaxyl». NASA. Archived from the original on August 23, 2014. Retrieved November 10, 2010.
  191. ^ Carretti, E.; Crocker, R. M.; Staveley-Smith, L.; Haverkorn, M.; Purcell, C.; Gaensler, B. M.; Bernardi, G.; Kesteven, M. J.; Poppi, S. (2013). «Giant magnetized outflows from the centre of the Milky Way». Nature. 493 (7430): 66–69. arXiv:1301.0512. Bibcode:2013Natur.493…66C. doi:10.1038/nature11734. PMID 23282363. S2CID 4426371.
  192. ^ Churchwell, E.; et al. (2009). «The Spitzer/GLIMPSE surveys: a new view of the Milky Way». Publications of the Astronomical Society of the Pacific. 121 (877): 213–230. Bibcode:2009PASP..121..213C. doi:10.1086/597811. S2CID 15529740.
  193. ^ Taylor, J. H.; Cordes, J. M. (1993). «Pulsar distances and the galactic distribution of free electrons». The Astrophysical Journal. 411: 674. Bibcode:1993ApJ…411..674T. doi:10.1086/172870.
  194. ^ a b c Russeil, D. (2003). «Star-forming complexes and the spiral structure of our Galaxy». Astronomy and Astrophysics. 397: 133–146. Bibcode:2003A&A…397..133R. doi:10.1051/0004-6361:20021504.
  195. ^ Dame, T. M.; Hartmann, D.; Thaddeus, P. (2001). «The Milky Way in molecular clouds: A new complete CO survey». The Astrophysical Journal. 547 (2): 792–813. arXiv:astro-ph/0009217. Bibcode:2001ApJ…547..792D. doi:10.1086/318388. S2CID 118888462.
  196. ^ a b c Benjamin, R. A. (2008). Beuther, H.; Linz, H.; Henning, T. (eds.). The Spiral Structure of the Galaxy: Something Old, Something New... Massive Star Formation: Observations Confront Theory. Vol. 387. Astronomical Society of the Pacific Conference Series. p. 375. Bibcode:2008ASPC..387..375B.
    See also Bryner, Jeanna (June 3, 2008). «New Images: Milky Way Loses Two Arms». Space.com. Archived from the original on June 4, 2008. Retrieved June 4, 2008.
  197. ^ a b c Majaess, D. J.; Turner, D. G.; Lane, D. J. (2009). «Searching Beyond the Obscuring Dust Between the Cygnus-Aquila Rifts for Cepheid Tracers of the Galaxy’s Spiral Arms». The Journal of the American Association of Variable Star Observers. 37 (2): 179. arXiv:0909.0897. Bibcode:2009JAVSO..37..179M.
  198. ^ Lépine, J. R. D.; et al. (2011). «The spiral structure of the Galaxy revealed by CS sources and evidence for the 4:1 resonance». Monthly Notices of the Royal Astronomical Society. 414 (2): 1607–1616. arXiv:1010.1790. Bibcode:2011MNRAS.414.1607L. doi:10.1111/j.1365-2966.2011.18492.x. S2CID 118477787.
  199. ^ a b Drimmel, R. (2000). «Evidence for a two-armed spiral in the Milky Way». Astronomy & Astrophysics. 358: L13–L16. arXiv:astro-ph/0005241. Bibcode:2000A&A…358L..13D.
  200. ^ Sanna, A.; Reid, M. J.; Dame, T. M.; Menten, K. M.; Brunthaler, A. (2017). «Mapping spiral structure on the far side of the Milky Way». Science. 358 (6360): 227–230. arXiv:1710.06489. Bibcode:2017Sci…358..227S. doi:10.1126/science.aan5452. PMID 29026043. S2CID 206660521.
  201. ^ a b McClure-Griffiths, N. M.; Dickey, J. M.; Gaensler, B. M.; Green, A. J. (2004). «A Distant Extended Spiral Arm in the Fourth Quadrant of the Milky Way». The Astrophysical Journal. 607 (2): L127. arXiv:astro-ph/0404448. Bibcode:2004ApJ…607L.127M. doi:10.1086/422031. S2CID 119327129.
  202. ^ Benjamin, R. A.; et al. (2005). «First GLIMPSE results on the stellar structure of the Galaxy». The Astrophysical Journal. 630 (2): L149–L152. arXiv:astro-ph/0508325. Bibcode:2005ApJ…630L.149B. doi:10.1086/491785. S2CID 14782284.
  203. ^ «Massive stars mark out Milky Way’s ‘missing’ arms» (Press release). Leeds, UK: University of Leeds. December 17, 2013. Archived from the original on December 18, 2013. Retrieved December 18, 2013.
  204. ^ Westerholm, Russell (December 18, 2013). «Milky Way Galaxy has four arms, reaffirming old data and contradicting recent research». University Herald. Archived from the original on December 19, 2013. Retrieved December 18, 2013.
  205. ^ a b Urquhart, J. S.; Figura, C. C.; Moore, T. J. T.; Hoare, M. G.; et al. (January 2014). «The RMS Survey: Galactic distribution of massive star formation». Monthly Notices of the Royal Astronomical Society. 437 (2): 1791–1807. arXiv:1310.4758. Bibcode:2014MNRAS.437.1791U. doi:10.1093/mnras/stt2006. S2CID 14266458.
  206. ^ van Woerden, H.; et al. (1957). «Expansion d’une structure spirale dans le noyau du Système Galactique, et position de la radiosource Sagittarius A». Comptes Rendus de l’Académie des Sciences (in French). 244: 1691–1695. Bibcode:1957CRAS..244.1691V.
  207. ^ a b Dame, T. M.; Thaddeus, P. (2008). «A New Spiral Arm of the Galaxy: The Far 3-Kpc Arm». The Astrophysical Journal. 683 (2): L143–L146. arXiv:0807.1752. Bibcode:2008ApJ…683L.143D. doi:10.1086/591669. S2CID 7450090.
  208. ^ «Milky Way’s Inner Beauty Revealed». Center for Astrophysics | Harvard & Smithsonian. June 3, 2008. Archived from the original on July 5, 2013. Retrieved July 7, 2015.
  209. ^ Matson, John (September 14, 2011). «Star-Crossed: Milky Way’s Spiral Shape May Result from a Smaller Galaxy’s Impact». Scientific American. Archived from the original on December 3, 2013. Retrieved July 7, 2015.
  210. ^ Mel’Nik, A.; Rautiainen, A. (2005). «Kinematics of the outer pseudorings and the spiral structure of the Galaxy». Astronomy Letters. 35 (9): 609–624. arXiv:0902.3353. Bibcode:2009AstL…35..609M. CiteSeerX 10.1.1.247.4658. doi:10.1134/s1063773709090047. S2CID 15989486.
  211. ^ Mel’Nik, A. (2006). «Outer pseudoring in the galaxy». Astronomische Nachrichten. 326 (7): 589–605. arXiv:astro-ph/0510569. Bibcode:2005AN….326Q.599M. doi:10.1002/asna.200585006. S2CID 117118657.
  212. ^ Lopez-Corredoira, M.; et al. (July 2012). «Comments on the «Monoceros» affair». arXiv:1207.2749 [astro-ph.GA].
  213. ^ Byrd, Deborah (February 5, 2019). «The Milky Way is warped». EarthSky. Archived from the original on February 6, 2019. Retrieved February 6, 2019.
  214. ^ Harris, William E. (February 2003). «Catalog of Parameters for Milky Way Globular Clusters: The Database» (text). SEDS. Archived from the original on March 9, 2012. Retrieved May 10, 2007.
  215. ^ Dauphole, B.; et al. (September 1996). «The kinematics of globular clusters, apocentric distances and a halo metallicity gradient». Astronomy and Astrophysics. 313: 119–128. Bibcode:1996A&A…313..119D.
  216. ^ Gnedin, O. Y.; Lee, H. M.; Ostriker, J. P. (1999). «Effects of Tidal Shocks on the Evolution of Globular Clusters». The Astrophysical Journal. 522 (2): 935–949. arXiv:astro-ph/9806245. Bibcode:1999ApJ…522..935G. doi:10.1086/307659. S2CID 11143134.
  217. ^ Janes, K.A.; Phelps, R.L. (1980). «The galactic system of old star clusters: The development of the galactic disk». The Astronomical Journal. 108: 1773–1785. Bibcode:1994AJ….108.1773J. doi:10.1086/117192.
  218. ^ Ibata, R.; et al. (2005). «On the accretion origin of a vast extended stellar disk around the Andromeda Galaxy». The Astrophysical Journal. 634 (1): 287–313. arXiv:astro-ph/0504164. Bibcode:2005ApJ…634..287I. doi:10.1086/491727. S2CID 17803544.
  219. ^ «Outer Disk Ring?». SolStation. Archived from the original on June 2, 2007. Retrieved May 10, 2007.
  220. ^ T.M. Dame; P. Thaddeus (2011). «A Molecular Spiral Arm in the Far Outer Galaxy». The Astrophysical Journal. 734 (1): L24. arXiv:1105.2523. Bibcode:2011ApJ…734L..24D. doi:10.1088/2041-8205/734/1/l24. S2CID 118301649.
  221. ^ Jurić, M.; et al. (February 2008). «The Milky Way Tomography with SDSS. I. Stellar Number Density Distribution». The Astrophysical Journal. 673 (2): 864–914. arXiv:astro-ph/0510520. Bibcode:2008ApJ…673..864J. doi:10.1086/523619. S2CID 11935446.
  222. ^ Boen, Brooke. «NASA’s Chandra Shows Milky Way is Surrounded by Halo of Hot Gas». Brooke Boen. Archived from the original on October 23, 2012. Retrieved October 28, 2012.
  223. ^ Gupta, A.; Mathur, S.; Krongold, Y.; Nicastro, F.; Galeazzi, M. (2012). «A Huge Reservoir of Ionized Gas Around the Milky Way: Accounting for the Missing Mass?». The Astrophysical Journal. 756 (1): L8. arXiv:1205.5037. Bibcode:2012ApJ…756L…8G. doi:10.1088/2041-8205/756/1/L8. S2CID 118567708.
  224. ^ «Galactic Halo: Milky Way is Surrounded by Huge Halo of Hot Gas». Smithsonian Astrophysical Observatory. September 24, 2012. Archived from the original on October 29, 2012.
  225. ^ Communications, Discovery. «Our Galaxy Swims Inside a Giant Pool of Hot Gas». Discovery Communications. Archived from the original on October 29, 2012. Retrieved October 28, 2012.
  226. ^ a b J.D. Harrington; Janet Anderson; Peter Edmonds (September 24, 2012). «NASA’s Chandra Shows Milky Way is Surrounded by Halo of Hot Gas». NASA. Archived from the original on October 23, 2012.
  227. ^ Peter Schneider (2006). Extragalactic Astronomy and Cosmology. Springer. page 4, Fig. 1.4. ISBN 978-3-540-33174-2.
  228. ^ Jones, Mark H.; Lambourne, Robert J.; Adams, David John (2004). An Introduction to Galaxies and Cosmology. Cambridge University Press. p. 21; Fig. 1.13. ISBN 978-0-521-54623-2.
  229. ^ Camarillo, Tia; Dredger, Pauline; Ratra, Bharat (May 4, 2018). «Median Statistics Estimate of the Galactic Rotational Velocity». Astrophysics and Space Science. 363 (12): 268. arXiv:1805.01917. Bibcode:2018Ap&SS.363..268C. doi:10.1007/s10509-018-3486-8. S2CID 55697732.
  230. ^ Peter Schneider (2006). Extragalactic Astronomy and Cosmology. Springer. p. 413. ISBN 978-3-540-33174-2.
  231. ^ a b Staff (July 27, 2017). «Milky Way’s origins are not what they seem». Phys.org. Archived from the original on July 27, 2017. Retrieved July 27, 2017.
  232. ^ Borah, Debasish; Dutta, Manoranjan; Mahapatra, Satyabrata; Sahu, Narendra (2022). «Boosted self-interacting dark matter and XENON1T excess». Nuclear Physics B. 979: 115787. arXiv:2107.13176. Bibcode:2022NuPhB.97915787B. doi:10.1016/j.nuclphysb.2022.115787. S2CID 236469147.
  233. ^ Legassick, Daniel (2015). «The Age Distribution of Potential Intelligent Life in the Milky Way». arXiv:1509.02832 [astro-ph.GA].
  234. ^ Wethington, Nicholas (May 27, 2009). «Formation of the Milky Way». Universe Today. Archived from the original on August 17, 2014.
  235. ^ a b Buser, R. (2000). «The Formation and Early Evolution of the Milky Way Galaxy». Science. 287 (5450): 69–74. Bibcode:2000Sci…287…69B. doi:10.1126/science.287.5450.69. PMID 10615051.
  236. ^ Wakker, B. P.; Van Woerden, H. (1997). «High-Velocity Clouds». Annual Review of Astronomy and Astrophysics. 35: 217–266. Bibcode:1997ARA&A..35..217W. doi:10.1146/annurev.astro.35.1.217. S2CID 117861711.
  237. ^ Lockman, F. J.; et al. (2008). «The Smith Cloud: A High-Velocity Cloud Colliding with the Milky Way». The Astrophysical Journal. 679 (1): L21–L24. arXiv:0804.4155. Bibcode:2008ApJ…679L..21L. doi:10.1086/588838. S2CID 118393177.
  238. ^ Kruijssen, J M Diederik; Pfeffer, Joel L; Chevance, Mélanie; Bonaca, Ana; Trujillo-Gomez, Sebastian; Bastian, Nate; Reina-Campos, Marta; Crain, Robert A; Hughes, Meghan E (October 2020). «Kraken reveals itself – the merger history of the Milky Way reconstructed with the E-MOSAICS simulations». Monthly Notices of the Royal Astronomical Society. 498 (2): 2472–2491. arXiv:2003.01119. doi:10.1093/mnras/staa2452. Retrieved November 15, 2020.
  239. ^ Young, Monica (November 13, 2020). «Star Clusters reveal the «Kraken» in the Milky Way’s Past». Sky and Telescope. Retrieved November 15, 2020.
  240. ^ Yin, J.; Hou, J.L; Prantzos, N.; Boissier, S.; et al. (2009). «Milky Way versus Andromeda: a tale of two disks». Astronomy and Astrophysics. 505 (2): 497–508. arXiv:0906.4821. Bibcode:2009A&A…505..497Y. doi:10.1051/0004-6361/200912316. S2CID 14344453.
  241. ^ Hammer, F.; Puech, M.; Chemin, L.; Flores, H.; et al. (2007). «The Milky Way, an Exceptionally Quiet Galaxy: Implications for the Formation of Spiral Galaxies». The Astrophysical Journal. 662 (1): 322–334. arXiv:astro-ph/0702585. Bibcode:2007ApJ…662..322H. doi:10.1086/516727. S2CID 18002823.
  242. ^ Mutch, S.J.; Croton, D.J.; Poole, G.B. (2011). «The Mid-life Crisis of the Milky Way and M31». The Astrophysical Journal. 736 (2): 84. arXiv:1105.2564. Bibcode:2011ApJ…736…84M. doi:10.1088/0004-637X/736/2/84. S2CID 119280671.
  243. ^ Licquia, T.; Newman, J.A.; Poole, G.B. (2012). «What Is The Color Of The Milky Way?». American Astronomical Society. 219: 252.08. Bibcode:2012AAS…21925208L.
  244. ^ «A firestorm of star birth (artist’s illustration)». www.spacetelescope.org. ESA/Hubble. Archived from the original on April 13, 2015. Retrieved April 14, 2015.
  245. ^ Cayrel; et al. (2001). «Measurement of stellar age from uranium decay». Nature. 409 (6821): 691–692. arXiv:astro-ph/0104357. Bibcode:2001Natur.409..691C. doi:10.1038/35055507. PMID 11217852. S2CID 17251766.
  246. ^ Cowan, J. J.; Sneden, C.; Burles, S.; Ivans, I. I.; Beers, T. C.; Truran, J. W.; Lawler, J. E.; Primas, F.; Fuller, G. M.; et al. (2002). «The Chemical Composition and Age of the Metal‐poor Halo Star BD +17o3248». The Astrophysical Journal. 572 (2): 861–879. arXiv:astro-ph/0202429. Bibcode:2002ApJ…572..861C. doi:10.1086/340347. S2CID 119503888.
  247. ^ Krauss, L. M.; Chaboyer, B. (2003). «Age Estimates of Globular Clusters in the Milky Way: Constraints on Cosmology». Science. 299 (5603): 65–69. Bibcode:2003Sci…299…65K. doi:10.1126/science.1075631. PMID 12511641. S2CID 10814581.
  248. ^ Johns Hopkins University (November 5, 2018). «Johns Hopkins scientist finds elusive star with origins close to Big Bang». EurekAlert!. Archived from the original on November 6, 2018. Retrieved November 5, 2018.
  249. ^ Rosen, Jill (November 5, 2018). «Johns Hopkins scientist finds elusive star with origins close to Big Bang – The newly discovered star’s composition indicates that, in a cosmic family tree, it could be as little as one generation removed from the Big Bang». Johns Hopkins University. Archived from the original on November 6, 2018. Retrieved November 5, 2018.
  250. ^ Schlaufman, Kevin C.; Thompson, Ian B.; Casey, Andrew R. (November 5, 2018). «An Ultra Metal-poor Star Near the Hydrogen-burning Limit». The Astrophysical Journal. 867 (2): 98. arXiv:1811.00549. Bibcode:2018ApJ…867…98S. doi:10.3847/1538-4357/aadd97. S2CID 54511945.
  251. ^ a b Frebel, A.; et al. (2007). «Discovery of HE 1523-0901, a strongly r-process-enhanced metal-poor star with detected uranium». The Astrophysical Journal. 660 (2): L117. arXiv:astro-ph/0703414. Bibcode:2007ApJ…660L.117F. doi:10.1086/518122. S2CID 17533424.
  252. ^ «Hubble Finds Birth Certificate of Oldest Known Star in the Milky Way». NASA. March 7, 2013. Archived from the original on August 11, 2014.
  253. ^ Specktor, Brandon (March 23, 2019). «Astronomers Find Fossils of Early Universe Stuffed in Milky Way’s Bulge». Live Science. Archived from the original on March 23, 2019. Retrieved March 24, 2019.
  254. ^ del Peloso, E. F. (2005). «The age of the Galactic thin disk from Th/Eu nucleocosmochronology. III. Extended sample». Astronomy and Astrophysics. 440 (3): 1153–1159. arXiv:astro-ph/0506458. Bibcode:2005A&A…440.1153D. doi:10.1051/0004-6361:20053307. S2CID 16484977.
  255. ^ Skibba, Ramon (2016), «Milky Way retired early from star making» (New Scientist, March 5, 2016), p.9
  256. ^ Lynden-Bell, D. (March 1, 1976). «Dwarf Galaxies and Globular Clusters in High Velocity Hydrogen Streams». Monthly Notices of the Royal Astronomical Society. 174 (3): 695–710. Bibcode:1976MNRAS.174..695L. doi:10.1093/mnras/174.3.695. ISSN 0035-8711.
  257. ^ Kroupa, P.; Theis, C.; Boily, C. M. (2005). «The great disk of Milky-Way satellites and cosmological sub-structures». Astronomy and Astrophysics. 431 (2): 517–521. arXiv:astro-ph/0410421. Bibcode:2005A&A…431..517K. doi:10.1051/0004-6361:20041122.
  258. ^ Tully, R. Brent; Shaya, Edward J.; Karachentsev, Igor D.; Courtois, Hélène M.; Kocevski, Dale D.; Rizzi, Luca; Peel, Alan (March 2008). «Our Peculiar Motion Away from the Local Void». The Astrophysical Journal. 676 (1): 184–205. arXiv:0705.4139. Bibcode:2008ApJ…676..184T. doi:10.1086/527428. S2CID 14738309.
  259. ^ Hadhazy, Adam (November 3, 2016). «Why Nothing Really Matters». Discover Magazine. Retrieved April 24, 2022.
  260. ^ R. Brent Tully; Helene Courtois; Yehuda Hoffman; Daniel Pomarède (September 2, 2014). «The Laniakea supercluster of galaxies». Nature (published September 4, 2014). 513 (7516): 71–73. arXiv:1409.0880. Bibcode:2014Natur.513…71T. doi:10.1038/nature13674. PMID 25186900. S2CID 205240232.
  261. ^ De Vaucouleurs, Gerard; De Vaucouleurs, Antoinette; Corwin, Herold G.; Buta, Ronald J.; Paturel, Georges; Fouque, Pascal (1991). Third Reference Catalogue of Bright Galaxies. Bibcode:1991rc3..book…..D. doi:10.1007/978-1-4757-4363-0. ISBN 978-1-4757-4365-4.
  262. ^ Putman, M. E.; Staveley‐Smith, L.; Freeman, K. C.; Gibson, B. K.; Barnes, D. G. (2003). «The Magellanic Stream, High‐Velocity Clouds, and the Sculptor Group». The Astrophysical Journal. 586 (1): 170–194. arXiv:astro-ph/0209127. Bibcode:2003ApJ…586..170P. doi:10.1086/344477. S2CID 6911875.
  263. ^ Sergey E. Koposov; Vasily Belokurov; Gabriel Torrealba; N. Wyn Evans (March 10, 2015). «Beasts of the Southern Wild. Discovery of a large number of Ultra Faint satellites in the vicinity of the Magellanic Clouds». The Astrophysical Journal. 805 (2): 130. arXiv:1503.02079. Bibcode:2015ApJ…805..130K. doi:10.1088/0004-637X/805/2/130. S2CID 118267222.
  264. ^ Noyola, E.; Gebhardt, K.; Bergmann, M. (April 2008). «Gemini and Hubble Space Telescope Evidence for an Intermediate-Mass Black Hole in ω Centauri». The Astrophysical Journal. 676 (2): 1008–1015. arXiv:0801.2782. Bibcode:2008ApJ…676.1008N. doi:10.1086/529002. S2CID 208867075.
  265. ^ Lea Kivivali (June 11, 2014). «Nearby satellite galaxies challenge standard model of galaxy formation». Swinburne University of Technology. Archived from the original on March 16, 2015.
  266. ^ Pawlowski; et al. (June 10, 2014). «Co-orbiting satellite galaxy structures are still in conflict with the distribution of primordial dwarf galaxies». Monthly Notices of the Royal Astronomical Society. 442 (3): 2362–2380. arXiv:1406.1799. Bibcode:2014MNRAS.442.2362P. doi:10.1093/mnras/stu1005. S2CID 85454047.
  267. ^ «Milky Way Galaxy is warped and vibrating like a drum» (Press release). University of California, Berkeley. January 9, 2006. Archived from the original on July 16, 2014. Retrieved October 18, 2007.
  268. ^ Wong, Janet (April 14, 2000). «Astrophysicist maps out our own galaxy’s end». University of Toronto. Archived from the original on January 8, 2007. Retrieved January 11, 2007.
  269. ^ Junko Ueda; et al. (2014). «Cold molecular gas in merger remnants. I. Formation of molecular gas disks». The Astrophysical Journal Supplement Series. 214 (1): 1. arXiv:1407.6873. Bibcode:2014ApJS..214….1U. doi:10.1088/0067-0049/214/1/1. S2CID 716993.
  270. ^ Schiavi, Riccardo; Capuzzo-Dolcetta, Roberto; Arca-Sedda, Manuel; Spera, Mario (October 2020). «Future merger of the Milky Way with the Andromeda galaxy and the fate of their supermassive black holes». Astronomy & Astrophysics. 642: A30. arXiv:2102.10938. Bibcode:2020A&A…642A..30S. doi:10.1051/0004-6361/202038674. S2CID 224991193.
  271. ^ «The Velocity of Our Galaxy: the End of a 40-Year Mystery». CEA/The Knowledge Factory. January 31, 2017. Retrieved May 5, 2022.
  272. ^ «The Milky Way is being pushed through space by a void called the Dipole Repeller». Wired UK. Retrieved May 5, 2022.
  273. ^ Kocevski, D. D.; Ebeling, H. (2006). «On the origin of the Local Group’s peculiar velocity». The Astrophysical Journal. 645 (2): 1043–1053. arXiv:astro-ph/0510106. Bibcode:2006ApJ…645.1043K. doi:10.1086/503666. S2CID 2760455.
  274. ^ Peirani, S; Defreitaspacheco, J (2006). «Mass determination of groups of galaxies: Effects of the cosmological constant». New Astronomy. 11 (4): 325–330. arXiv:astro-ph/0508614. Bibcode:2006NewA…11..325P. doi:10.1016/j.newast.2005.08.008. S2CID 685068.
  275. ^ Lausten, Svend; Madsen, Claus; West, Richard M. (1987). Exploring the Southern Sky: a Pictorial Atlas from the European Southern Observatory (ESO). Berlin, Heidelberg: Springer. p. 119. ISBN 978-3-642-61588-7. OCLC 851764943.
  276. ^ Pasachoff, Jay M. (1994). Astronomy: From the Earth to the Universe. Harcourt School. p. 500. ISBN 978-0-03-001667-7.
  277. ^ Jones, Barrie William (2008). The Search for Life Continued: Planets Around Other Stars. Berlin: Springer. p. 89. ISBN 978-0-387-76559-4. OCLC 288474262.
  278. ^ Kruit, Pieter C. van der (2019). Jan Hendrik Oort: Master of the Galactic System. Cham, Switzerland: Springer. pp. 65, 717. ISBN 978-3-030-17801-7. OCLC 1110483488.
  279. ^ Hodge, Paul W.; et al. (October 13, 2020). «Milky Way Galaxy». Encyclopædia Britannica.

Further reading[edit]

  • Dambeck, Thorsten Dambeck (March 2008). «Gaia’s Mission to the Milky Way». Sky & Telescope: 36–39.
  • Chiappini, Cristina (November–December 2001). «The Formation and Evolution of the Milky Way» (PDF). American Scientist. 89 (6): 506–515. doi:10.1511/2001.40.745.

External links[edit]

Wikiquote has quotations related to Milky Way.

  • Milky Way – IRAS (infrared) survey – wikisky.org
  • Milky Way – H-Alpha survey – wikisky.org
  • Multiwavelength Milky Way – Images and VRML models (NASA)
  • Milky Way – Panorama (9 billion pixels).
  • Milky Way – SEDS Messier website
  • Milky Way – Infrared Images
  • Milky Way – Mosaic of galactic plane (March 19, 2021)
Milky Way
ESO-VLT-Laser-phot-33a-07.jpg

The Galactic Center as seen from Earth’s night sky (the laser creates a guide-star for the telescope)
Observation data (J2000 epoch)
Constellation Sagittarius
Right ascension 17h 45m 40.03599s[1]
Declination −29° 00′ 28.1699″[1]
Distance 7.935–8.277 kpc (25,881–26,996 ly)[2][3][4][a]
Characteristics
Type Sb; Sbc; SB(rs)bc[5][6]
Mass 1.15×1012[7] M☉
Number of stars 100–400 billion ((1–4)×1011)[9][10]
Size 26.8 ± 1.1 kpc (87,400 ± 3,590 ly)
(diameter; 25.0 mag/arcsec2 B-band isophote)[8]
Thickness of thin disk 220–450 pc (718–1,470 ly)[11]
Thickness of thick disk 2.6 ± 0.5 kpc (8,500 ± 1,600 ly)[11]
Angular momentum ≈1×1067 J s[12]
Sun’s Galactic rotation period 212 Myr[13]
Spiral pattern rotation period 220–360 Myr[14]
Bar pattern rotation period 160–180 Myr[15]
Speed relative to CMB rest frame 552.2±5.5 km/s[16]
Escape velocity at Sun’s position 550 km/s[17]
Dark matter density at Sun’s position 0.0088+0.0024
−0.0018 M☉pc−3 (0.35+0.08
−0.07 GeV cm−3)[17]

The Milky Way[b] is the galaxy that includes our Solar System, with the name describing the galaxy’s appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. The term Milky Way is a translation of the Latin via lactea, from the Greek γαλακτικός κύκλος (galaktikos kýklos), meaning «milky circle».[18][19][20] From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe.[21] Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Doust Curtis,[22] observations by Edwin Hubble showed that the Milky Way is just one of many galaxies.

The Milky Way is a barred spiral galaxy with an estimated D25 isophotal diameter of 26.8 ± 1.1 kiloparsecs (87,400 ± 3,590 light-years),[8] but only about 1,000 light years thick at the spiral arms (more at the bulge). Recent simulations suggest that a dark matter area, also containing some visible stars, may extend up to a diameter of almost 2 million light-years (613 kpc).[23][24] The Milky Way has several satellite galaxies and is part of the Local Group of galaxies, which form part of the Virgo Supercluster, which is itself a component of the Laniakea Supercluster.[25][26]

It is estimated to contain 100–400 billion stars[27][28] and at least that number of planets.[29][30] The Solar System is located at a radius of about 27,000 light-years (8.3 kpc) from the Galactic Center,[31] on the inner edge of the Orion Arm, one of the spiral-shaped concentrations of gas and dust. The stars in the innermost 10,000 light-years form a bulge and one or more bars that radiate from the bulge. The Galactic Center is an intense radio source known as Sagittarius A*, a supermassive black hole of 4.100 (± 0.034) million solar masses.[32][33] Stars and gases at a wide range of distances from the Galactic Center orbit at approximately 220 kilometers per second. The constant rotational speed appears to contradict the laws of Keplerian dynamics and suggests that much (about 90%)[34][35] of the mass of the Milky Way is invisible to telescopes, neither emitting nor absorbing electromagnetic radiation. This conjectural mass has been termed «dark matter».[36] The rotational period is about 212 million years at the radius of the Sun.[13]

The Milky Way as a whole is moving at a velocity of approximately 600 km per second with respect to extragalactic frames of reference. The oldest stars in the Milky Way are nearly as old as the Universe itself and thus probably formed shortly after the Dark Ages of the Big Bang.[37]

Etymology and mythology[edit]

The Origin of the Milky Way by Tintoretto (circa 1575–1580)

In the Babylonian epic poem Enūma Eliš, the Milky Way is created from the severed tail of the primeval salt water dragoness Tiamat, set in the sky by Marduk, the Babylonian national god, after slaying her.[38][39] This story was once thought to have been based on an older Sumerian version in which Tiamat is instead slain by Enlil of Nippur,[40][41] but is now thought to be purely an invention of Babylonian propagandists with the intention to show Marduk as superior to the Sumerian deities.[41]

In Greek mythology, Zeus places his son born by a mortal woman, the infant Heracles, on Hera’s breast while she is asleep so the baby will drink her divine milk and thus become immortal. Hera wakes up while breastfeeding and then realizes she is nursing an unknown baby: she pushes the baby away, some of her milk spills, and it produces the band of light known as the Milky Way. In another Greek story, the abandoned Heracles is given by Athena to Hera for feeding, but Heracles’ forcefulness causes Athena to rip him from her breast in pain.[42][43][44]

Llys Dôn (literally «The Court of Dôn») is the traditional Welsh name for the constellation Cassiopeia. At least three of Dôn’s children also have astronomical associations: Caer Gwydion («The fortress of Gwydion») is the traditional Welsh name for the Milky Way,[45][46] and Caer Arianrhod («The Fortress of Arianrhod») being the constellation of Corona Borealis.[47][48]

In western culture, the name «Milky Way» is derived from its appearance as a dim un-resolved «milky» glowing band arching across the night sky. The term is a translation of the Classical Latin via lactea, in turn derived from the Hellenistic Greek γαλαξίας, short for γαλαξίας κύκλος (galaxías kýklos), meaning «milky circle». The Ancient Greek γαλαξίας (galaxias) – from root γαλακτ-, γάλα («milk») + -ίας (forming adjectives) – is also the root of «galaxy», the name for our, and later all such, collections of stars.[18][49][50][51]

The Milky Way, or «milk circle», was just one of 11 «circles» the Greeks identified in the sky, others being the zodiac, the meridian, the horizon, the equator, the tropics of Cancer and Capricorn, the Arctic Circle and the Antarctic Circle, and two colure circles passing through both poles.[52]

Appearance[edit]

The Milky Way is visible as a hazy band of white light, some 30° wide, arching the night sky.[53] Although all the individual naked-eye stars in the entire sky are part of the Milky Way Galaxy, the term «Milky Way» is limited to this band of light.[54][55] The light originates from the accumulation of unresolved stars and other material located in the direction of the galactic plane. Brighter regions around the band appear as soft visual patches known as star clouds. The most conspicuous of these is the Large Sagittarius Star Cloud, a portion of the central bulge of the galaxy.[56] Dark regions within the band, such as the Great Rift and the Coalsack, are areas where interstellar dust blocks light from distant stars. Peoples of the southern hemisphere, including the Inca and Australian aborigines, identified these regions as dark cloud constellations.[57] The area of sky that the Milky Way obscures is called the Zone of Avoidance.[58]

The Milky Way has a relatively low surface brightness. Its visibility can be greatly reduced by background light, such as light pollution or moonlight. The sky needs to be darker than about 20.2 magnitude per square arcsecond in order for the Milky Way to be visible.[59] It should be visible if the limiting magnitude is approximately +5.1 or better and shows a great deal of detail at +6.1.[60] This makes the Milky Way difficult to see from brightly lit urban or suburban areas, but very prominent when viewed from rural areas when the Moon is below the horizon.[c] Maps of artificial night sky brightness show that more than one-third of Earth’s population cannot see the Milky Way from their homes due to light pollution.[61]

As viewed from Earth, the visible region of the Milky Way’s galactic plane occupies an area of the sky that includes 30 constellations.[d] The Galactic Center lies in the direction of Sagittarius, where the Milky Way is brightest. From Sagittarius, the hazy band of white light appears to pass around to the galactic anticenter in Auriga. The band then continues the rest of the way around the sky, back to Sagittarius, dividing the sky into two roughly equal hemispheres.[citation needed]

The galactic plane is inclined by about 60° to the ecliptic (the plane of Earth’s orbit). Relative to the celestial equator, it passes as far north as the constellation of Cassiopeia and as far south as the constellation of Crux, indicating the high inclination of Earth’s equatorial plane and the plane of the ecliptic, relative to the galactic plane. The north galactic pole is situated at right ascension 12h 49m, declination +27.4° (B1950) near β Comae Berenices, and the south galactic pole is near α Sculptoris. Because of this high inclination, depending on the time of night and year, the Milky Way arch may appear relatively low or relatively high in the sky. For observers from latitudes approximately 65° north to 65° south, the Milky Way passes directly overhead twice a day.[citation needed]

  • The Milky Way arching at a high inclination across the night sky, (this composited panorama was taken at Paranal Observatory in northern Chile); the Magellanic Clouds can be seen on the left; the bright object near top center is Jupiter in the constellation Sagittarius, and the orange glow at the horizon on the right is Antofagasta city with a jet trail above it; galactic north is downward.

    The Milky Way arching at a high inclination across the night sky, (this composited panorama was taken at Paranal Observatory in northern Chile); the Magellanic Clouds can be seen on the left; the bright object near top center is Jupiter in the constellation Sagittarius, and the orange glow at the horizon on the right is Antofagasta city with a jet trail above it; galactic north is downward.

  • The Milky Way viewed at different wavelengths

    The Milky Way viewed at different wavelengths

Astronomical history[edit]

The shape of the Milky Way as deduced from star counts by William Herschel in 1785; the Solar System was assumed near center

In Meteorologica, Aristotle (384–322 BC) states that the Greek philosophers Anaxagoras (c. 500–428 BC) and Democritus (460–370 BC) proposed that the Milky Way is the glow of stars not directly visible due to Earth’s shadow, while other stars receive their light from the Sun (but have their glow obscured by solar rays).[62] Aristotle himself believed that the Milky Way was part of the Earth’s upper atmosphere (along with the stars), and that it was a byproduct of stars burning that did not dissipate because of its outermost location in the atmosphere (composing its great circle). He also said that the Milky appearance of the Milky Way galaxy was due to the refraction of the earth’s atmosphere.[63][64][65] The Neoplatonist philosopher Olympiodorus the Younger (c. 495–570 AD) criticized this view, arguing that if the Milky Way were sublunary, it should appear different at different times and places on Earth, and that it should have parallax, which it does not. In his view, the Milky Way is celestial. This idea would be influential later in the Muslim world.[66]

The Persian astronomer Al-Biruni (973–1048) proposed that the Milky Way is «a collection of countless fragments of the nature of nebulous stars».[67] The Andalusian astronomer Avempace (d 1138) proposed the Milky Way to be made up of many stars but appears to be a continuous image in the Earth’s atmosphere, citing his observation of a conjunction of Jupiter and Mars in 1106 or 1107 as evidence.[64] The Persian astronomer Nasir al-Din al-Tusi (1201–1274) in his Tadhkira wrote: «The Milky Way, i.e. the Galaxy, is made up of a very large number of small, tightly clustered stars, which, on account of their concentration and smallness, seem to be cloudy patches. Because of this, it was likened to milk in color.»[68] Ibn Qayyim al-Jawziyya (1292–1350) proposed that the Milky Way is «a myriad of tiny stars packed together in the sphere of the fixed stars».[69]

Proof of the Milky Way consisting of many stars came in 1610 when Galileo Galilei used a telescope to study the Milky Way and discovered that it is composed of a huge number of faint stars. Galileo also concluded that the appearance of the Milky Way was due to refraction of the Earth’s atmosphere .[70][71][63] In a treatise in 1755, Immanuel Kant, drawing on earlier work by Thomas Wright,[72] speculated (correctly) that the Milky Way might be a rotating body of a huge number of stars, held together by gravitational forces akin to the Solar System but on much larger scales.[73] The resulting disk of stars would be seen as a band on the sky from our perspective inside the disk. Wright and Kant also conjectured that some of the nebulae visible in the night sky might be separate «galaxies» themselves, similar to our own. Kant referred to both the Milky Way and the «extragalactic nebulae» as «island universes», a term still current up to the 1930s.[74][75][76]

The first attempt to describe the shape of the Milky Way and the position of the Sun within it was carried out by William Herschel in 1785 by carefully counting the number of stars in different regions of the visible sky. He produced a diagram of the shape of the Milky Way with the Solar System close to the center.[77]

In 1845, Lord Rosse constructed a new telescope and was able to distinguish between elliptical and spiral-shaped nebulae. He also managed to make out individual point sources in some of these nebulae, lending credence to Kant’s earlier conjecture.[78][79]

Photograph of the «Great Andromeda Nebula» from 1899, later identified as the Andromeda Galaxy

In 1904, studying the proper motions of stars, Jacobus Kapteyn reported that these were not random, as it was believed in that time; stars could be divided into two streams, moving in nearly opposite directions.[80] It was later realized that Kapteyn’s data had been the first evidence of the rotation of our galaxy,[81] which ultimately led to the finding of galactic rotation by Bertil Lindblad and Jan Oort.[citation needed]

In 1917, Heber Curtis had observed the nova S Andromedae within the Great Andromeda Nebula (Messier object 31). Searching the photographic record, he found 11 more novae. Curtis noticed that these novae were, on average, 10 magnitudes fainter than those that occurred within the Milky Way. As a result, he was able to come up with a distance estimate of 150,000 parsecs. He became a proponent of the «island universes» hypothesis, which held that the spiral nebulae were independent galaxies.[82][83] In 1920 the Great Debate took place between Harlow Shapley and Heber Curtis, concerning the nature of the Milky Way, spiral nebulae, and the dimensions of the Universe. To support his claim that the Great Andromeda Nebula is an external galaxy, Curtis noted the appearance of dark lanes resembling the dust clouds in the Milky Way, as well as the significant Doppler shift.[84]

The controversy was conclusively settled by Edwin Hubble in the early 1920s using the Mount Wilson observatory 2.5 m (100 in) Hooker telescope. With the light-gathering power of this new telescope, he was able to produce astronomical photographs that resolved the outer parts of some spiral nebulae as collections of individual stars. He was also able to identify some Cepheid variables that he could use as a benchmark to estimate the distance to the nebulae. He found that the Andromeda Nebula is 275,000 parsecs from the Sun, far too distant to be part of the Milky Way.[85][86]

Astrography[edit]

An all-sky view of stars in the Milky Way and neighbouring galaxies, based on the first year of observations from Gaia satellite, from July 2014 to September 2015. The map shows the density of stars in each portion of the sky. Brighter regions indicate denser concentrations of stars. Darker regions across the Galactic Plane correspond to dense clouds of interstellar gas and dust that absorb starlight.

The ESA spacecraft Gaia provides distance estimates by determining the parallax of a billion stars and is mapping the Milky Way with four planned releases of maps in 2016, 2018, 2021 and 2024.[87][88]
Data from Gaia has been described as «transformational». It has been estimated that Gaia has expanded the number of observations of stars from about 2 million stars as of the 1990s to 2 billion. It has expanded the measurable volume of space by a factor of 100 in radius and a factor of 1,000 in precision.[89]
A study in 2020 concluded that Gaia detected a wobbling motion of the galaxy, which might be caused by «torques from a misalignment of the disc’s rotation axis with respect to the principal axis of a non-spherical halo, or from accreted matter in the halo acquired during late infall, or from nearby, interacting satellite galaxies and their consequent tides».[90]

Sun’s location and neighborhood[edit]

Position of the Solar System within the Milky Way

Diagram of the Milky Way with the position of the Solar System marked by a yellow arrow and a red dot in the Orion Arm. The dot roughly covers the larger surroundings of the Solar System, the space between the Radcliffe wave and Split linear structures (formerly the Gould Belt).[91]

Artistic close-up of the Orion Arm with the main features of the Radcliffe Wave and Split linear structures, and with the Solar System surrounded by the closest large scale celestial features at the surface of the Local Bubble at a distance of 400–500 light years.

The Sun is near the inner rim of the Orion Arm, within the Local Fluff of the Local Bubble, between the Radcliffe wave and Split linear structures (formerly Gould Belt).[91] Based upon studies of stellar orbits around Sgr A* by Gillessen et al. (2016), the Sun lies at an estimated distance of 27.14 ± 0.46 kly (8.32 ± 0.14 kpc)[31] from the Galactic Center. Boehle et al. (2016) found a smaller value of 25.64 ± 0.46 kly (7.86 ± 0.14 kpc), also using a star orbit analysis.[92] The Sun is currently 5–30 parsecs (16–98 ly) above, or north of, the central plane of the Galactic disk.[93] The distance between the local arm and the next arm out, the Perseus Arm, is about 2,000 parsecs (6,500 ly).[94] The Sun, and thus the Solar System, is located in the Milky Way’s galactic habitable zone.[95][96]

There are about 208 stars brighter than absolute magnitude 8.5 within a sphere with a radius of 15 parsecs (49 ly) from the Sun, giving a density of one star per 69 cubic parsecs, or one star per 2,360 cubic light-years (from List of nearest bright stars). On the other hand, there are 64 known stars (of any magnitude, not counting 4 brown dwarfs) within 5 parsecs (16 ly) of the Sun, giving a density of about one star per 8.2 cubic parsecs, or one per 284 cubic light-years (from List of nearest stars). This illustrates the fact that there are far more faint stars than bright stars: in the entire sky, there are about 500 stars brighter than apparent magnitude 4 but 15.5 million stars brighter than apparent magnitude 14.[97]

The apex of the Sun’s way, or the solar apex, is the direction that the Sun travels through space in the Milky Way. The general direction of the Sun’s Galactic motion is towards the star Vega near the constellation of Hercules, at an angle of roughly 60 sky degrees to the direction of the Galactic Center. The Sun’s orbit about the Milky Way is expected to be roughly elliptical with the addition of perturbations due to the Galactic spiral arms and non-uniform mass distributions. In addition, the Sun passes through the Galactic plane approximately 2.7 times per orbit.[98] This is very similar to how a simple harmonic oscillator works with no drag force (damping) term. These oscillations were until recently thought to coincide with mass lifeform extinction periods on Earth.[99] A reanalysis of the effects of the Sun’s transit through the spiral structure based on CO data has failed to find a correlation.[100]

It takes the Solar System about 240 million years to complete one orbit of the Milky Way (a galactic year),[101] so the Sun is thought to have completed 18–20 orbits during its lifetime and 1/1250 of a revolution since the origin of humans. The orbital speed of the Solar System about the center of the Milky Way is approximately 220 km/s (490,000 mph) or 0.073% of the speed of light. The Sun moves through the heliosphere at 84,000 km/h (52,000 mph). At this speed, it takes around 1,400 years for the Solar System to travel a distance of 1 light-year, or 8 days to travel 1 AU (astronomical unit).[102] The Solar System is headed in the direction of the zodiacal constellation Scorpius, which follows the ecliptic.[103]

Galactic quadrants[edit]

A galactic quadrant, or quadrant of the Milky Way, refers to one of four circular sectors in the division of the Milky Way. In astronomical practice, the delineation of the galactic quadrants is based upon the galactic coordinate system, which places the Sun as the origin of the mapping system.[104]

Quadrants are described using ordinals – for example, «1st galactic quadrant»,[105] «second galactic quadrant»,[106] or «third quadrant of the Milky Way».[107] Viewing from the north galactic pole with 0° (zero degrees) as the ray that runs starting from the Sun and through the Galactic Center, the quadrants are:

Galactic
quadrant
  		Galactic
longitude
(ℓ) 		 
Reference
 
1st 0° ≤ ℓ ≤ 90°   [108]
2nd   90° ≤ ℓ ≤ 180° [106]
3rd 180° ≤ ℓ ≤ 270° [107]
4th
  		270° ≤ ℓ ≤ 360°
(360° ≅ 0°) 		[105]
 

with the galactic longitude (ℓ) increasing in the counter-clockwise direction (positive rotation) as viewed from north of the Galactic Center (a view-point several hundred thousand light-years distant from Earth in the direction of the constellation Coma Berenices); if viewed from south of the Galactic Center (a view-point similarly distant in the constellation Sculptor), ℓ would increase in the clockwise direction (negative rotation).

Size and mass[edit]

The structure of the Milky Way is thought to be similar to this galaxy (UGC 12158 imaged by Hubble)

Size[edit]

A size comparison of the six largest galaxies of the Local Group, together with the Milky Way

The Milky Way is one of the two largest galaxies in the Local Group (the other being the Andromeda Galaxy), although the size for its galactic disc and how much it defines the isophotal diameter is not well understood.[109] It is estimated that the significant bulk of stars in the galaxy lies within the 26 kiloparsecs (80,000 light-years) diameter, and that the number of stars beyond the outermost disc dramatically reduces to a very low number, with respect to an extrapolation of the exponential disk with the scale length of the inner disc.[110][109]

There are several methods being used in astronomy in defining the size of a galaxy, and each of them can yield different results with respect to one another. The most commonly employed method is the D25 standard – the isophote where the photometric brightness of a galaxy in the B-band (445 nm wavelength of light, in the blue part of the visible spectrum) reaches 25 mag/arcsec2.[111] An estimate from 1997 by Goodwin and others compared the distribution of Cepheid variable stars in 17 other spiral galaxies to the ones in the Milky Way, and modelling the relationship to their surface brightnesses. This gave an isophotal diameter for the Milky Way at 26.8 ± 1.1 kiloparsecs (87,400 ± 3,590 light-years), by assuming that the galactic disc is well represented by an exponential disc and adopting a central surface brightness of the galaxy (µ0) of 22.1±0.3 B-mag/arcsec−2 and a disk scale length (h) of 5.0 ± 0.5 kpc (16,000 ± 1,600 ly).[112][8][113] This is significantly smaller than the Andromeda Galaxy’s isophotal diameter, and slightly below the mean isophotal sizes of the galaxies being at 28.3 kpc (92,000 ly).[8] The paper concludes that the Milky Way and Andromeda Galaxy were not overly large spiral galaxies and as well as one of the largest known (if the former not being the largest) as previously widely believed, but rather average ordinary spiral galaxies.[114] To compare the relative physical scale of the Milky Way, if the Solar System out to Neptune were the size of a US quarter (24.3 mm (0.955 in)), the Milky Way would be approximately at least the greatest north–south line of the contiguous United States.[115] An even older study from 1978 gave a lower diameter for Milky Way about 23 kpc (75,000 ly).[8]

A 2015 paper discovered that there is a ring-like filament of stars called Triangulum–Andromeda Ring (TriAnd Ring) rippling above and below the relatively flat galactic plane, which alongside Monoceros Ring were both suggested to be primarily the result of disk oscillations and wrapping around the Milky Way, at a diameter of at least 50 kpc (160,000 ly),[116] which may be part of the Milky Way’s outer disk itself, hence making the stellar disk larger by increasing to this size.[117] However, a more recent 2018 paper later somewhat ruled out this hypothesis, and supported a conclusion that the Monoceros Ring, A13 and TriAnd Ring were stellar overdensities rather kicked out from the main stellar disk, with the velocity dispersion of the RR Lyrae stars found to be higher and consistent with halo membership.[118] Another 2018 study revealed the very probable presence of disk stars at 26–31.5 kpc (84,800–103,000 ly) from the Galactic Center or perhaps even farther, significantly beyond approximately 13–20 kpc (40,000–70,000 ly), in which it was once believed to be the abrupt drop-off of the stellar density of the disk, meaning that few or no stars were expected to be above this limit, save for stars that belong to the old population of the galactic halo.[109][119][120]

A 2020 study predicted the edge of the Milky Way’s dark matter halo being around 292 ± 61 kpc (952,000 ± 199,000 ly), which translates to a diameter of 584 ± 122 kpc (1.905 ± 0.3979 Mly).[23][24] The Milky Way’s stellar disk is also estimated to be approximately up to 1.35 kpc (4,000 ly) thick.[121][122]

A schematic profile of the Milky Way.
Abbreviations: GNP/GSP: Galactic North and South Poles

Mass[edit]

The Milky Way is approximately 890 billion to 1.54 trillion times the mass of the Sun in total (8.9×1011 to 1.54×1012 solar masses),[34][35][123] although stars and planets make up only a small part of this. Estimates of the mass of the Milky Way vary, depending upon the method and data used. The low end of the estimate range is 5.8×1011 solar masses (M☉), somewhat less than that of the Andromeda Galaxy.[124][125][126] Measurements using the Very Long Baseline Array in 2009 found velocities as large as 254 km/s (570,000 mph) for stars at the outer edge of the Milky Way.[127] Because the orbital velocity depends on the total mass inside the orbital radius, this suggests that the Milky Way is more massive, roughly equaling the mass of Andromeda Galaxy at 7×1011 M☉ within 160,000 ly (49 kpc) of its center.[128] In 2010, a measurement of the radial velocity of halo stars found that the mass enclosed within 80 kiloparsecs is 7×1011 M☉.[129] According to a study published in 2014, the mass of the entire Milky Way is estimated to be 8.5×1011 M☉,[130] but this is only half the mass of the Andromeda Galaxy.[130] A recent 2019 mass estimate for the Milky Way is 1.29×1012 M☉.[131]

Much of the mass of the Milky Way seems to be dark matter, an unknown and invisible form of matter that interacts gravitationally with ordinary matter. A dark matter halo is conjectured to spread out relatively uniformly to a distance beyond one hundred kiloparsecs (kpc) from the Galactic Center. Mathematical models of the Milky Way suggest that the mass of dark matter is 1–1.5×1012 M☉.[132][133][134] 2013 and 2014 studies indicate a range in mass, as large as 4.5×1012 M☉[135] and as small as 8×1011 M☉.[136] By comparison, the total mass of all the stars in the Milky Way is estimated to be between 4.6×1010 M☉[137] and 6.43×1010 M☉.[132] In addition to the stars, there is also interstellar gas, comprising 90% hydrogen and 10% helium by mass,[138] with two thirds of the hydrogen found in the atomic form and the remaining one-third as molecular hydrogen.[139] The mass of the Milky Way’s interstellar gas is equal to between 10%[139] and 15%[138] of the total mass of its stars. Interstellar dust accounts for an additional 1% of the total mass of the gas.[138]

In March 2019, astronomers reported that the virial mass of the Milky Way galaxy is 1.54 trillion solar masses within a radius of about 39.5 kpc (130,000 ly), over twice as much as was determined in earlier studies, and suggesting that about 90% of the mass of the galaxy is dark matter.[34][35]

Contents[edit]

360-degree panorama view of the Milky Way (an assembled mosaic of photographs) by ESO, the galactic centre is in the middle of the view, with galactic north up

360-degree rendering of the Milky Way using Gaia EDR3 data showing interstellar gas, dust backlit by stars (main patches labeled in black; white labels are main bright patches of stars). Left hemisphere is facing the galactic center, right hemisphere is facing the galactic anticenter.

The Milky Way contains between 100 and 400 billion stars[9][10] and at least that many planets.[140] An exact figure would depend on counting the number of very-low-mass stars, which are difficult to detect, especially at distances of more than 300 ly (90 pc) from the Sun. As a comparison, the neighboring Andromeda Galaxy contains an estimated one trillion (1012) stars.[141] The Milky Way may contain ten billion white dwarfs, a billion neutron stars, and a hundred million stellar black holes.[e][142][143] Filling the space between the stars is a disk of gas and dust called the interstellar medium. This disk has at least a comparable extent in radius to the stars,[144] whereas the thickness of the gas layer ranges from hundreds of light-years for the colder gas to thousands of light-years for warmer gas.[145][146]

The disk of stars in the Milky Way does not have a sharp edge beyond which there are no stars. Rather, the concentration of stars decreases with distance from the center of the Milky Way. For reasons that are not understood, beyond a radius of roughly 40,000 light years (13 kpc) from the center, the number of stars per cubic parsec drops much faster with radius.[110] Surrounding the galactic disk is a spherical galactic halo of stars and globular clusters that extends farther outward, but is limited in size by the orbits of two Milky Way satellites, the Large and Small Magellanic Clouds, whose closest approach to the Galactic Center is about 180,000 ly (55 kpc).[147] At this distance or beyond, the orbits of most halo objects would be disrupted by the Magellanic Clouds. Hence, such objects would probably be ejected from the vicinity of the Milky Way. The integrated absolute visual magnitude of the Milky Way is estimated to be around −20.9.[148][149][f]

Both gravitational microlensing and planetary transit observations indicate that there may be at least as many planets bound to stars as there are stars in the Milky Way,[29][150] and microlensing measurements indicate that there are more rogue planets not bound to host stars than there are stars.[151][152] The Milky Way contains at least one planet per star, resulting in 100–400 billion planets, according to a January 2013 study of the five-planet star system Kepler-32 by the Kepler space observatory.[30] A different January 2013 analysis of Kepler data estimated that at least 17 billion Earth-sized exoplanets reside in the Milky Way.[153] On November 4, 2013, astronomers reported, based on Kepler space mission data, that there could be as many as 40 billion Earth-sized planets orbiting in the habitable zones of Sun-like stars and red dwarfs within the Milky Way.[154][155][156] 11 billion of these estimated planets may be orbiting Sun-like stars.[157] The nearest exoplanet may be 4.2 light-years away, orbiting the red dwarf Proxima Centauri, according to a 2016 study.[158] Such Earth-sized planets may be more numerous than gas giants,[29] though harder to detect at great distances given their small size. Besides exoplanets, «exocomets», comets beyond the Solar System, have also been detected and may be common in the Milky Way.[159] More recently, in November 2020, over 300 million habitable exoplanets are estimated to exist in the Milky Way Galaxy.[160]

Structure[edit]

Overview of different elements of the overall structure of the Milky Way.

A dark spot surrounded by doughnut shaped orange-yellow ring

Artist’s impression of how the Milky Way would look from different vantage points – from edge-on lines-of-sight, the peanut-shell-shaped structure, not to be confused with the galaxy’s central bulge, is evident; viewed from above, the central narrow bar that is responsible for this structure appears clearly, as would many spiral arms and their associated dust clouds

The Milky Way consists of a bar-shaped core region surrounded by a warped disk of gas, dust and stars.[162][163] The mass distribution within the Milky Way closely resembles the type Sbc in the Hubble classification, which represents spiral galaxies with relatively loosely wound arms.[5] Astronomers first began to conjecture that the Milky Way is a barred spiral galaxy, rather than an ordinary spiral galaxy, in the 1960s.[164][165][166] These conjectures were confirmed by the Spitzer Space Telescope observations in 2005 that showed the Milky Way’s central bar to be larger than previously thought.[167]

Galactic Center[edit]

The Sun is 25,000–28,000 ly (7.7–8.6 kpc) from the Galactic Center. This value is estimated using geometric-based methods or by measuring selected astronomical objects that serve as standard candles, with different techniques yielding various values within this approximate range.[168][92][31][169][170][171] In the inner few kiloparsecs (around 10,000 light-years radius) is a dense concentration of mostly old stars in a roughly spheroidal shape called the bulge.[172] It has been proposed that the Milky Way lacks a bulge due to a collision and merger between previous galaxies, and that instead it only has a pseudobulge formed by its central bar.[173] However, confusion in the literature between the (peanut shell)-shaped structure created by instabilities in the bar, versus a possible bulge with an expected half-light radius of 0.5 kpc, abounds.[174]

The Galactic Center is marked by an intense radio source named Sagittarius A* (pronounced Sagittarius A-star). The motion of material around the center indicates that Sagittarius A* harbors a massive, compact object.[175] This concentration of mass is best explained as a supermassive black hole[g][168][176] (SMBH) with an estimated mass of 4.1–4.5 million times the mass of the Sun.[176] The rate of accretion of the SMBH is consistent with an inactive galactic nucleus, being estimated at 1×10−5 M☉ per year.[177] Observations indicate that there are SMBHs located near the center of most normal galaxies.[178][179]

The nature of the Milky Way’s bar is actively debated, with estimates for its half-length and orientation spanning from 1 to 5 kpc (3,000–16,000 ly) and 10–50 degrees relative to the line of sight from Earth to the Galactic Center.[170][171][180] Certain authors advocate that the Milky Way features two distinct bars, one nestled within the other.[181] However, RR Lyrae-type stars do not trace a prominent Galactic bar.[171][182][183] The bar may be surrounded by a ring called the «5 kpc ring» that contains a large fraction of the molecular hydrogen present in the Milky Way, as well as most of the Milky Way’s star formation activity. Viewed from the Andromeda Galaxy, it would be the brightest feature of the Milky Way.[184] X-ray emission from the core is aligned with the massive stars surrounding the central bar[177] and the Galactic ridge.[185]

Gamma rays and x-rays[edit]

Since 1970, various gamma-ray detection missions have discovered 511-keV gamma rays coming from the general direction of the Galactic Center. These gamma rays are produced by positrons (antielectrons) annihilating with electrons. In 2008 it was found that the distribution of the sources of the gamma rays resembles the distribution of low-mass X-ray binaries, seeming to indicate that these X-ray binaries are sending positrons (and electrons) into interstellar space where they slow down and annihilate.[186][187][188] The observations were both made by NASA and ESA’s satellites. In 1970 gamma ray detectors found that the emitting region was about 10,000 light-years across with a luminosity of about 10,000 suns.[187]

Illustration of the two gigantic X-ray/gamma-ray bubbles (blue-violet) of the Milky Way (center)

In 2010, two gigantic spherical bubbles of high energy gamma-emission were detected to the north and the south of the Milky Way core, using data from the Fermi Gamma-ray Space Telescope. The diameter of each of the bubbles is about 25,000 light-years (7.7 kpc) (or about 1/4 of the galaxy’s estimated diameter); they stretch up to Grus and to Virgo on the night-sky of the southern hemisphere.[189][190] Subsequently, observations with the Parkes Telescope at radio frequencies identified polarized emission that is associated with the Fermi bubbles. These observations are best interpreted as a magnetized outflow driven by star formation in the central 640 ly (200 pc) of the Milky Way.[191]

Later, on January 5, 2015, NASA reported observing an X-ray flare 400 times brighter than usual, a record-breaker, from Sagittarius A*. The unusual event may have been caused by the breaking apart of an asteroid falling into the black hole or by the entanglement of magnetic field lines within gas flowing into Sagittarius A*.[161]

Spiral arms[edit]

Outside the gravitational influence of the Galactic bar, the structure of the interstellar medium and stars in the disk of the Milky Way is organized into four spiral arms.[192] Spiral arms typically contain a higher density of interstellar gas and dust than the Galactic average as well as a greater concentration of star formation, as traced by H II regions[193][194] and molecular clouds.[195]

The Milky Way’s spiral structure is uncertain, and there is currently no consensus on the nature of the Milky Way’s arms.[196] Perfect logarithmic spiral patterns only crudely describe features near the Sun,[194][197] because galaxies commonly have arms that branch, merge, twist unexpectedly, and feature a degree of irregularity.[171][197][198] The possible scenario of the Sun within a spur / Local arm[194] emphasizes that point and indicates that such features are probably not unique, and exist elsewhere in the Milky Way.[197] Estimates of the pitch angle of the arms range from about 7° to 25°.[144][199] There are thought to be four spiral arms that all start near the Milky Way Galaxy’s center.[200] These are named as follows, with the positions of the arms shown in the image below:

Observed (normal lines) and extrapolated (dotted lines) structure of the spiral arms of the Milky Way, viewed from north of the galaxy – the galaxy rotates clockwise in this view. The gray lines radiating from the Sun’s position (upper center) list the three-letter abbreviations of the corresponding constellations

Color Arm(s)
turquoise Near 3 kpc Arm and Perseus Arm
blue Norma and Outer arm (Along with extension discovered in 2004[201])
green Scutum–Centaurus Arm
red Carina–Sagittarius Arm
There are at least two smaller arms or spurs, including:
orange Orion–Cygnus Arm (which contains the Sun and Solar System)

Spitzer reveals what cannot be seen in visible light: cooler stars (blue), heated dust (reddish hue), and Sgr A* as bright white spot in the middle.

Artist’s conception of the spiral structure of the Milky Way with two major stellar arms and a bar.[196]

Two spiral arms, the Scutum–Centaurus arm and the Carina–Sagittarius arm, have tangent points inside the Sun’s orbit about the center of the Milky Way. If these arms contain an overdensity of stars compared to the average density of stars in the Galactic disk, it would be detectable by counting the stars near the tangent point. Two surveys of near-infrared light, which is sensitive primarily to red giants and not affected by dust extinction, detected the predicted overabundance in the Scutum–Centaurus arm but not in the Carina–Sagittarius arm: the Scutum–Centaurus Arm contains approximately 30% more red giants than would be expected in the absence of a spiral arm.[199][202] This observation suggests that the Milky Way possesses only two major stellar arms: the Perseus arm and the Scutum–Centaurus arm. The rest of the arms contain excess gas but not excess old stars.[196] In December 2013, astronomers found that the distribution of young stars and star-forming regions matches the four-arm spiral description of the Milky Way.[203][204][205] Thus, the Milky Way appears to have two spiral arms as traced by old stars and four spiral arms as traced by gas and young stars. The explanation for this apparent discrepancy is unclear.[205]

Clusters detected by WISE used to trace the Milky Way’s spiral arms.

The Near 3 kpc Arm (also called the Expanding 3 kpc Arm or simply the 3 kpc Arm) was discovered in the 1950s by astronomer van Woerden and collaborators through 21 centimeter radio measurements of HI (atomic hydrogen).[206][207] It was found to be expanding away from the central bulge at more than 50 km/s. It is located in the fourth galactic quadrant at a distance of about 5.2 kpc from the Sun and 3.3 kpc from the Galactic Center. The Far 3 kpc Arm was discovered in 2008 by astronomer Tom Dame (Center for Astrophysics | Harvard & Smithsonian). It is located in the first galactic quadrant at a distance of 3 kpc (about 10,000 ly) from the Galactic Center.[207][208]

A simulation published in 2011 suggested that the Milky Way may have obtained its spiral arm structure as a result of repeated collisions with the Sagittarius Dwarf Elliptical Galaxy.[209]

It has been suggested that the Milky Way contains two different spiral patterns: an inner one, formed by the Sagittarius arm, that rotates fast and an outer one, formed by the Carina and Perseus arms, whose rotation velocity is slower and whose arms are tightly wound. In this scenario, suggested by numerical simulations of the dynamics of the different spiral arms, the outer pattern would form an outer pseudoring,[210] and the two patterns would be connected by the Cygnus arm.[211]

The long filamentary molecular cloud dubbed «Nessie» probably forms a dense «spine» of the Scutum–Centarus Arm

Outside of the major spiral arms is the Monoceros Ring (or Outer Ring), a ring of gas and stars torn from other galaxies billions of years ago. However, several members of the scientific community recently restated their position affirming the Monoceros structure is nothing more than an over-density produced by the flared and warped thick disk of the Milky Way.[212] The structure of the Milky Way’s disk is warped along an «S» curve.[213]

Halo[edit]

The Galactic disk is surrounded by a spheroidal halo of old stars and globular clusters, of which 90% lie within 100,000 light-years (30 kpc) of the Galactic Center.[214] However, a few globular clusters have been found farther, such as PAL 4 and AM 1 at more than 200,000 light-years from the Galactic Center. About 40% of the Milky Way’s clusters are on retrograde orbits, which means they move in the opposite direction from the Milky Way rotation.[215] The globular clusters can follow rosette orbits about the Milky Way, in contrast to the elliptical orbit of a planet around a star.[216]

Although the disk contains dust that obscures the view in some wavelengths, the halo component does not. Active star formation takes place in the disk (especially in the spiral arms, which represent areas of high density), but does not take place in the halo, as there is little cool gas to collapse into stars.[101] Open clusters are also located primarily in the disk.[217]

Discoveries in the early 21st century have added dimension to the knowledge of the Milky Way’s structure. With the discovery that the disk of the Andromeda Galaxy (M31) extends much farther than previously thought,[218] the possibility of the disk of the Milky Way extending farther is apparent, and this is supported by evidence from the discovery of the Outer Arm extension of the Cygnus Arm[201][219] and of a similar extension of the Scutum–Centaurus Arm.[220] With the discovery of the Sagittarius Dwarf Elliptical Galaxy came the discovery of a ribbon of galactic debris as the polar orbit of the dwarf and its interaction with the Milky Way tears it apart. Similarly, with the discovery of the Canis Major Dwarf Galaxy, it was found that a ring of galactic debris from its interaction with the Milky Way encircles the Galactic disk.[citation needed]

The Sloan Digital Sky Survey of the northern sky shows a huge and diffuse structure (spread out across an area around 5,000 times the size of a full moon) within the Milky Way that does not seem to fit within current models. The collection of stars rises close to perpendicular to the plane of the spiral arms of the Milky Way. The proposed likely interpretation is that a dwarf galaxy is merging with the Milky Way. This galaxy is tentatively named the Virgo Stellar Stream and is found in the direction of Virgo about 30,000 light-years (9 kpc) away.[221]

Gaseous halo[edit]

In addition to the stellar halo, the Chandra X-ray Observatory, XMM-Newton, and Suzaku have provided evidence that there is a gaseous halo with a large amount of hot gas. The halo extends for hundreds of thousand of light-years, much farther than the stellar halo and close to the distance of the Large and Small Magellanic Clouds. The mass of this hot halo is nearly equivalent to the mass of the Milky Way itself.[222][223][224] The temperature of this halo gas is between 1 and 2.5 million K (1.8 and 4.5 million °F).[225]

Observations of distant galaxies indicate that the Universe had about one-sixth as much baryonic (ordinary) matter as dark matter when it was just a few billion years old. However, only about half of those baryons are accounted for in the modern Universe based on observations of nearby galaxies like the Milky Way.[226] If the finding that the mass of the halo is comparable to the mass of the Milky Way is confirmed, it could be the identity of the missing baryons around the Milky Way.[226]

Galactic rotation[edit]

Galaxy rotation curve for the Milky Way – vertical axis is speed of rotation about the galactic center; horizontal axis is distance from the galactic center in kpcs; the sun is marked with a yellow ball; the observed curve of speed of rotation is blue; the predicted curve based upon stellar mass and gas in the Milky Way is red; scatter in observations roughly indicated by gray bars, the difference is due to dark matter[36][227][228]

The stars and gas in the Milky Way rotate about its center differentially, meaning that the rotation period varies with location. As is typical for spiral galaxies, the orbital speed of most stars in the Milky Way does not depend strongly on their distance from the center. Away from the central bulge or outer rim, the typical stellar orbital speed is between 210 ± 10 km/s (470,000 ± 22,000 mph).[229] Hence the orbital period of the typical star is directly proportional only to the length of the path traveled. This is unlike the situation within the Solar System, where two-body gravitational dynamics dominate, and different orbits have significantly different velocities associated with them. The rotation curve (shown in the figure) describes this rotation. Toward the center of the Milky Way the orbit speeds are too low, whereas beyond 7 kpcs the speeds are too high to match what would be expected from the universal law of gravitation.[citation needed]

If the Milky Way contained only the mass observed in stars, gas, and other baryonic (ordinary) matter, the rotational speed would decrease with distance from the center. However, the observed curve is relatively flat, indicating that there is additional mass that cannot be detected directly with electromagnetic radiation. This inconsistency is attributed to dark matter.[36] The rotation curve of the Milky Way agrees with the universal rotation curve of spiral galaxies, the best evidence for the existence of dark matter in galaxies. Alternatively, a minority of astronomers propose that a modification of the law of gravity may explain the observed rotation curve.[230]

Formation[edit]

History[edit]

The Milky Way began as one or several small overdensities in the mass distribution in the Universe shortly after the Big Bang 13.61 billion years ago.[231][232][233] Some of these overdensities were the seeds of globular clusters in which the oldest remaining stars in what is now the Milky Way formed. Nearly half the matter in the Milky Way may have come from other distant galaxies.[231] Nonetheless, these stars and clusters now comprise the stellar halo of the Milky Way. Within a few billion years of the birth of the first stars, the mass of the Milky Way was large enough so that it was spinning relatively quickly. Due to conservation of angular momentum, this led the gaseous interstellar medium to collapse from a roughly spheroidal shape to a disk. Therefore, later generations of stars formed in this spiral disk. Most younger stars, including the Sun, are observed to be in the disk.[234][235]

Since the first stars began to form, the Milky Way has grown through both galaxy mergers (particularly early in the Milky Way’s growth) and accretion of gas directly from the Galactic halo.[235] The Milky Way is currently accreting material from several small galaxies, including two of its largest satellite galaxies, the Large and Small Magellanic Clouds, through the Magellanic Stream. Direct accretion of gas is observed in high-velocity clouds like the Smith Cloud.[236][237] Cosmological simulations indicate that, 11 billion years ago, it merged with a particularly large galaxy that has been labeled the Kraken.[238][239] However, properties of the Milky Way such as stellar mass, angular momentum, and metallicity in its outermost regions suggest it has undergone no mergers with large galaxies in the last 10 billion years. This lack of recent major mergers is unusual among similar spiral galaxies; its neighbour the Andromeda Galaxy appears to have a more typical history shaped by more recent mergers with relatively large galaxies.[240][241]

According to recent studies, the Milky Way as well as the Andromeda Galaxy lie in what in the galaxy color–magnitude diagram is known as the «green valley», a region populated by galaxies in transition from the «blue cloud» (galaxies actively forming new stars) to the «red sequence» (galaxies that lack star formation). Star-formation activity in green valley galaxies is slowing as they run out of star-forming gas in the interstellar medium. In simulated galaxies with similar properties, star formation will typically have been extinguished within about five billion years from now, even accounting for the expected, short-term increase in the rate of star formation due to the collision between both the Milky Way and the Andromeda Galaxy.[242] In fact, measurements of other galaxies similar to the Milky Way suggest it is among the reddest and brightest spiral galaxies that are still forming new stars and it is just slightly bluer than the bluest red sequence galaxies.[243]

Age and cosmological history[edit]

Comparison of the night sky with the night sky of a hypothetical planet within the Milky Way 10 billion years ago, at an age of about 3.6 billion years and 5 billion years before the Sun formed.[244]

Globular clusters are among the oldest objects in the Milky Way, which thus set a lower limit on the age of the Milky Way. The ages of individual stars in the Milky Way can be estimated by measuring the abundance of long-lived radioactive elements such as thorium-232 and uranium-238, then comparing the results to estimates of their original abundance, a technique called nucleocosmochronology. These yield values of about 12.5 ± 3 billion years for CS 31082-001[245] and 13.8 ± 4 billion years for BD +17° 3248.[246] Once a white dwarf is formed, it begins to undergo radiative cooling and the surface temperature steadily drops. By measuring the temperatures of the coolest of these white dwarfs and comparing them to their expected initial temperature, an age estimate can be made. With this technique, the age of the globular cluster M4 was estimated as 12.7 ± 0.7 billion years. Age estimates of the oldest of these clusters gives a best fit estimate of 12.6 billion years, and a 95% confidence upper limit of 16 billion years.[247]

In November 2018, astronomers reported the discovery of one of the oldest stars in the universe. About 13.5 billion-years-old, 2MASS J18082002-5104378 B is a tiny ultra metal-poor (UMP) star made almost entirely of materials released from the Big Bang, and is possibly one of the first stars. The discovery of the star in the Milky Way galaxy suggests that the galaxy may be at least 3 billion years older than previously thought.[248][249][250]

Several individual stars have been found in the Milky Way’s halo with measured ages very close to the 13.80-billion-year age of the Universe. In 2007, a star in the galactic halo, HE 1523-0901, was estimated to be about 13.2 billion years old. As the oldest known object in the Milky Way at that time, this measurement placed a lower limit on the age of the Milky Way.[251] This estimate was made using the UV-Visual Echelle Spectrograph of the Very Large Telescope to measure the relative strengths of spectral lines caused by the presence of thorium and other elements created by the R-process. The line strengths yield abundances of different elemental isotopes, from which an estimate of the age of the star can be derived using nucleocosmochronology.[251] Another star, HD 140283, is 14.5 ± 0.7 billion years old.[37][252]

According to observations utilizing adaptive optics to correct for Earth’s atmospheric distortion, stars in the galaxy’s bulge date to about 12.8 billion years old.[253]

The age of stars in the galactic thin disk has also been estimated using nucleocosmochronology. Measurements of thin disk stars yield an estimate that the thin disk formed 8.8 ± 1.7 billion years ago. These measurements suggest there was a hiatus of almost 5 billion years between the formation of the galactic halo and the thin disk.[254] Recent analysis of the chemical signatures of thousands of stars suggests that stellar formation might have dropped by an order of magnitude at the time of disk formation, 10 to 8 billion years ago, when interstellar gas was too hot to form new stars at the same rate as before.[255]

The satellite galaxies surrounding the Milky way are not randomly distributed but seem to be the result of a break-up of some larger system producing a ring structure 500,000 light-years in diameter and 50,000 light-years wide.[256] Close encounters between galaxies, like that expected in 4 billion years with the Andromeda Galaxy rips off huge tails of gas, which, over time can coalesce to form dwarf galaxies in a ring at an arbitrary angle to the main disc.[257]

Intergalactic neighbourhood[edit]

Diagram of the galaxies in the Local Group relative to the Milky Way

The Milky Way and the Andromeda Galaxy are a binary system of giant spiral galaxies belonging to a group of 50 closely bound galaxies known as the Local Group, surrounded by a Local Void, itself being part of the Local Sheet[258] and in turn the Virgo Supercluster. Surrounding the Virgo Supercluster are a number of voids, devoid of many galaxies, the Microscopium Void to the «north», the Sculptor Void to the «left», the Boötes Void to the «right» and the Canes-Major Void to the «south». These voids change shape over time, creating filamentous structures of galaxies. The Virgo Supercluster, for instance, is being drawn towards the Great Attractor,[259] which in turn forms part of a greater structure, called Laniakea.[260]

Two smaller galaxies and a number of dwarf galaxies in the Local Group orbit the Milky Way. The largest of these is the Large Magellanic Cloud with a diameter of 32,200 light-years.[261] It has a close companion, the Small Magellanic Cloud. The Magellanic Stream is a stream of neutral hydrogen gas extending from these two small galaxies across 100° of the sky. The stream is thought to have been dragged from the Magellanic Clouds in tidal interactions with the Milky Way.[262] Some of the dwarf galaxies orbiting the Milky Way are Canis Major Dwarf (the closest), Sagittarius Dwarf Elliptical Galaxy, Ursa Minor Dwarf, Sculptor Dwarf, Sextans Dwarf, Fornax Dwarf, and Leo I Dwarf. The smallest dwarf galaxies of the Milky Way are only 500 light-years in diameter. These include Carina Dwarf, Draco Dwarf, and Leo II Dwarf. There may still be undetected dwarf galaxies that are dynamically bound to the Milky Way, which is supported by the detection of nine new satellites of the Milky Way in a relatively small patch of the night sky in 2015.[263] There are also some dwarf galaxies that have already been absorbed by the Milky Way, such as the progenitor of Omega Centauri.[264]

In 2014 researchers reported that most satellite galaxies of the Milky Way lie in a very large disk and orbit in the same direction.[265] This came as a surprise: according to standard cosmology, the satellite galaxies should form in dark matter halos, and they should be widely distributed and moving in random directions. This discrepancy is still not fully explained.[266]

In January 2006, researchers reported that the heretofore unexplained warp in the disk of the Milky Way has now been mapped and found to be a ripple or vibration set up by the Large and Small Magellanic Clouds as they orbit the Milky Way, causing vibrations when they pass through its edges. Previously, these two galaxies, at around 2% of the mass of the Milky Way, were considered too small to influence the Milky Way. However, in a computer model, the movement of these two galaxies creates a dark matter wake that amplifies their influence on the larger Milky Way.[267]

Current measurements suggest the Andromeda Galaxy is approaching us at 100 to 140 km/s (220,000 to 310,000 mph). In 4.3 billion years, there may be an Andromeda–Milky Way collision, depending on the importance of unknown lateral components to the galaxies’ relative motion. If they collide, the chance of individual stars colliding with each other is extremely low,[268] but instead the two galaxies will merge to form a single elliptical galaxy or perhaps a large disk galaxy[269] over the course of about six billion years.[270]

Velocity[edit]

Although special relativity states that there is no «preferred» inertial frame of reference in space with which to compare the Milky Way, the Milky Way does have a velocity with respect to cosmological frames of reference.

One such frame of reference is the Hubble flow, the apparent motions of galaxy clusters due to the expansion of space. Individual galaxies, including the Milky Way, have peculiar velocities relative to the average flow. Thus, to compare the Milky Way to the Hubble flow, one must consider a volume large enough so that the expansion of the Universe dominates over local, random motions. A large enough volume means that the mean motion of galaxies within this volume is equal to the Hubble flow. Astronomers believe the Milky Way is moving at approximately 630 km/s (1,400,000 mph) with respect to this local co-moving frame of reference.[271][272] The Milky Way is moving in the general direction of the Great Attractor and other galaxy clusters, including the Shapley Supercluster, behind it.[273] The Local Group (a cluster of gravitationally bound galaxies containing, among others, the Milky Way and the Andromeda Galaxy) is part of a supercluster called the Local Supercluster, centered near the Virgo Cluster: although they are moving away from each other at 967 km/s (2,160,000 mph) as part of the Hubble flow, this velocity is less than would be expected given the 16.8 million pc distance due to the gravitational attraction between the Local Group and the Virgo Cluster.[274]

Another reference frame is provided by the cosmic microwave background (CMB), in which the CMB temperature is least distorted by Doppler shift (zero dipole moment). The Milky Way is moving at 552 ± 6 km/s (1,235,000 ± 13,000 mph)[16] with respect to this frame, toward 10.5 right ascension, −24° declination (J2000 epoch, near the center of Hydra). This motion is observed by satellites such as the Cosmic Background Explorer (COBE) and the Wilkinson Microwave Anisotropy Probe (WMAP) as a dipole contribution to the CMB, as photons in equilibrium in the CMB frame get blue-shifted in the direction of the motion and red-shifted in the opposite direction.[16]

See also[edit]

  • Baade’s Window
  • Galactic astronomy
  • Galactic Center GeV excess
  • Oort constants

Notes[edit]

  1. ^ a b The distance towards its center (Sagittarius A*).
  2. ^ a b Some authors use the term Milky Way to refer exclusively to the band of light that the galaxy forms in the night sky, while the galaxy receives the full name Milky Way Galaxy. See for example Lausten et al.,[275] Pasachoff,[276] Jones,[277] van der Kruit,[278] and Hodge et al.[279]
  3. ^ See also Bortle Dark-Sky Scale.
  4. ^ The bright center of the galaxy is located in the constellation Sagittarius. From Sagittarius, the hazy band of white light appears to pass westward through the constellations of Scorpius, Ara, Norma, Triangulum Australe, Circinus, Centaurus, Musca, Crux, Carina, Vela, Puppis, Canis Major, Monoceros, Orion and Gemini, Taurus, to the galactic anticenter in Auriga. From there, it passes through Perseus, Andromeda, Cassiopeia, Cepheus and Lacerta, Cygnus, Vulpecula, Sagitta, Aquila, Ophiuchus, Scutum, and back to Sagittarius.
  5. ^ These estimates are very uncertain, as most non-star objects are difficult to detect; for example, black hole estimates range from ten million to one billion.[280][281]
  6. ^ Karachentsev et al. give a blue absolute magnitude of −20.8. Combined with a color index of 0.55 estimated here, an absolute visual magnitude of −21.35 (−20.8 − 0.55 = −21.35) is obtained. Note that determining the absolute magnitude of the Milky Way is very difficult, because Earth is inside it.
  7. ^ For a photo see: «Sagittarius A*: Milky Way monster stars in cosmic reality show». Chandra X-ray Observatory. Center for Astrophysics | Harvard & Smithsonian. January 6, 2003. Archived from the original on March 17, 2008. Retrieved May 20, 2012.

Cite error: A list-defined reference has no name (see the help page).

Cite error: A list-defined reference has no name (see the help page).

References[edit]

  1. ^ a b Petrov, L.; Kovalev, Y. Y.; Fomalont, E. B.; Gordon, D. (2011). «The Very Long Baseline Array Galactic Plane Survey—VGaPS». The Astronomical Journal. 142 (2): 35. arXiv:1101.1460. Bibcode:2011AJ….142…35P. doi:10.1088/0004-6256/142/2/35. S2CID 121762178.
  2. ^ Event Horizon Telescope Collaboration; et al. (2022). «First Sagittarius A* Event Horizon Telescope Results. VI. Testing the Black Hole Metric». The Astrophysical Journal. 930 (2): L17. Bibcode:2022ApJ…930L..17E. doi:10.3847/2041-8213/ac6756. S2CID 248744741.
  3. ^ Banerjee, Indrani; Sau, Subhadip; SenGupta, Soumitra (2022). «Do shadows of SGR A* and M87* indicate black holes with a magnetic monopole charge?». arXiv:2207.06034 [gr-qc].
  4. ^ Abuter, R.; et al. (2019). «A geometric distance measurement to the Galactic center black hole with 0.3% uncertainty». Astronomy & Astrophysics. 625: L10. arXiv:1904.05721. Bibcode:2019A&A…625L..10G. doi:10.1051/0004-6361/201935656. S2CID 119190574.
  5. ^ a b Gerhard, O. (2002). «Mass distribution in our Galaxy». Space Science Reviews. 100 (1/4): 129–138. arXiv:astro-ph/0203110. Bibcode:2002SSRv..100..129G. doi:10.1023/A:1015818111633. S2CID 42162871.
  6. ^ Frommert, Hartmut; Kronberg, Christine (August 26, 2005). «Classification of the Milky Way Galaxy». SEDS. Archived from the original on May 31, 2015. Retrieved May 30, 2015.
  7. ^ Carlesi, Edoardo; Hoffman, Yehuda; Libeskind, Noam I. (2022). «Estimation of the masses in the local group by gradient boosted decision trees». Monthly Notices of the Royal Astronomical Society. 513 (2): 2385–2393. arXiv:2204.03334. doi:10.1093/mnras/stac897.
  8. ^ a b c d e Goodwin, S. P.; Gribbin, J.; Hendry, M. A. (August 1998). «The relative size of the Milky Way». The Observatory. 118: 201–208. Bibcode:1998Obs…118..201G.
  9. ^ a b Frommert, H.; Kronberg, C. (August 25, 2005). «The Milky Way Galaxy». SEDS. Archived from the original on May 12, 2007. Retrieved May 9, 2007.
  10. ^ a b Wethington, Nicholos. «How Many Stars are in the Milky Way?». Archived from the original on March 27, 2010. Retrieved April 9, 2010.
  11. ^ a b Bland-Hawthorn, Joss; Gerhard, Ortwin (2016). «The Galaxy in Context: Structural, Kinematic, and Integrated Properties». Annual Review of Astronomy and Astrophysics. 54: 529–596. arXiv:1602.07702. Bibcode:2016ARA&A..54..529B. doi:10.1146/annurev-astro-081915-023441. S2CID 53649594.
  12. ^ Karachentsev, Igor. «Double Galaxies § 7.1». ned.ipac.caltech.edu. Izdatel’stvo Nauka. Archived from the original on March 4, 2016. Retrieved April 5, 2015.
  13. ^ a b «A New Map of the Milky Way». Scientific American. April 1, 2020.
  14. ^ Gerhard, O. (2010). «Pattern speeds in the Milky Way». arXiv:1003.2489v1.
  15. ^ Shen, Juntai; Zheng, Xing-Wu (2020). «The bar and spiral arms in the Milky Way: Structure and kinematics». Research in Astronomy and Astrophysics. 20 (10): 159. arXiv:2012.10130. Bibcode:2020RAA….20..159S. doi:10.1088/1674-4527/20/10/159. S2CID 229005996.
  16. ^ a b c Kogut, Alan; et al. (December 10, 1993). «Dipole anisotropy in the COBE differential microwave radiometers first-year sky maps». The Astrophysical Journal. 419: 1…6. arXiv:astro-ph/9312056. Bibcode:1993ApJ…419….1K. doi:10.1086/173453. S2CID 209835274.
  17. ^ a b Kafle, P.R.; Sharma, S.; Lewis, G.F.; Bland-Hawthorn, J. (2014). «On the Shoulders of Giants: Properties of the Stellar Halo and the Milky Way Mass Distribution». The Astrophysical Journal. 794 (1): 17. arXiv:1408.1787. Bibcode:2014ApJ…794…59K. doi:10.1088/0004-637X/794/1/59. S2CID 119040135.
  18. ^ a b Harper, Douglas. «galaxy». Online Etymology Dictionary. Archived from the original on May 27, 2012. Retrieved May 20, 2012.
  19. ^ Jankowski, Connie (2010). Pioneers of Light and Sound. Compass Point Books. p. 6. ISBN 978-0-7565-4306-8. Archived from the original on November 20, 2016.
  20. ^ Schiller, Jon (2010). Big Bang & Black Holes. CreateSpace. p. 163. ISBN 978-1-4528-6552-2. Archived from the original on November 20, 2016.
  21. ^ «Milky Way Galaxy: Facts About Our Galactic Home». Space.com. Archived from the original on March 21, 2017. Retrieved April 8, 2017.
  22. ^ Shapley, H.; Curtis, H. D. (1921). «The Scale of the Universe». Bulletin of the National Research Council. 2 (11): 171–217. Bibcode:1921BuNRC…2..171S.
  23. ^ a b Croswell, Ken (March 23, 2020). «Astronomers have found the edge of the Milky Way at last». ScienceNews. Archived from the original on March 24, 2020. Retrieved March 27, 2020.
  24. ^ a b Dearson, Alis J. (2020). «The Edge of the Galaxy». Monthly Notices of the Royal Astronomical Society. 496 (3): 3929–3942. arXiv:2002.09497. Bibcode:2020MNRAS.496.3929D. doi:10.1093/mnras/staa1711. S2CID 211259409.
  25. ^ «Laniakea: Our home supercluster». youtube.com. Archived from the original on September 4, 2014.
  26. ^ Tully, R. Brent; et al. (September 4, 2014). «The Laniakea supercluster of galaxies». Nature. 513 (7516): 71–73. arXiv:1409.0880. Bibcode:2014Natur.513…71T. doi:10.1038/nature13674. PMID 25186900. S2CID 205240232.
  27. ^ «Milky Way». BBC. Archived from the original on March 2, 2012.
  28. ^ «How Many Stars in the Milky Way?». NASA Blueshift. Archived from the original on January 25, 2016.
  29. ^ a b c Cassan, A.; et al. (January 11, 2012). «One or more bound planets per Milky Way star from microlensing observations». Nature. 481 (7380): 167–169. arXiv:1202.0903. Bibcode:2012Natur.481..167C. doi:10.1038/nature10684. PMID 22237108. S2CID 2614136.
  30. ^ a b Staff (January 2, 2013). «100 Billion Alien Planets Fill Our Milky Way Galaxy: Study». Space.com. Archived from the original on January 3, 2013. Retrieved January 3, 2013.
  31. ^ a b c Gillessen, Stefan; Plewa, Philipp; Eisenhauer, Frank; Sari, Re’em; Waisberg, Idel; Habibi, Maryam; Pfuhl, Oliver; George, Elizabeth; Dexter, Jason; von Fellenberg, Sebastiano; Ott, Thomas; Genzel, Reinhard (November 28, 2016). «An Update on Monitoring Stellar Orbits in the Galactic Center». The Astrophysical Journal. 837 (1): 30. arXiv:1611.09144. Bibcode:2017ApJ…837…30G. doi:10.3847/1538-4357/aa5c41. S2CID 119087402.
  32. ^ Overbye, Dennis (January 31, 2022). «An Electrifying View of the Heart of the Milky Way – A new radio-wave image of the center of our galaxy reveals all the forms of frenzy that a hundred million or so stars can get up to». The New York Times. Archived from the original on January 31, 2022. Retrieved February 1, 2022.
  33. ^ Heyood, I.; et al. (January 28, 2022). «The 1.28 GHz MeerKAT Galactic Center Mosaic». The Astrophysical Journal. 925 (2): 165. arXiv:2201.10541. Bibcode:2022ApJ…925..165H. doi:10.3847/1538-4357/ac449a. S2CID 246275657.
  34. ^ a b c Starr, Michelle (March 8, 2019). «The Latest Calculation of Milky Way’s Mass Just Changed What We Know About Our Galaxy». ScienceAlert.com. Archived from the original on March 8, 2019. Retrieved March 8, 2019.
  35. ^ a b c Watkins, Laura L.; et al. (February 2, 2019). «Evidence for an Intermediate-Mass Milky Way from Gaia DR2 Halo Globular Cluster Motions». The Astrophysical Journal. 873 (2): 118. arXiv:1804.11348. Bibcode:2019ApJ…873..118W. doi:10.3847/1538-4357/ab089f. S2CID 85463973.
  36. ^ a b c Koupelis, Theo; Kuhn, Karl F. (2007). In Quest of the Universe. Jones & Bartlett Publishers. p. 492, Fig. 16–13. ISBN 978-0-7637-4387-1.
  37. ^ a b H.E. Bond; E. P. Nelan; D. A. VandenBerg; G. H. Schaefer; et al. (February 13, 2013). «HD 140283: A Star in the Solar Neighborhood that Formed Shortly After the Big Bang». The Astrophysical Journal. 765 (1): L12. arXiv:1302.3180. Bibcode:2013ApJ…765L..12B. doi:10.1088/2041-8205/765/1/L12. S2CID 119247629.
  38. ^ Brown, William P. (2010). The Seven Pillars of Creation: The Bible, Science, and the Ecology of Wonder. Oxford, England: Oxford University Press. p. 25. ISBN 978-0-19-973079-7.
  39. ^ MacBeath, Alastair (1999). Tiamat’s Brood: An Investigation Into the Dragons of Ancient Mesopotamia. Dragon’s Head. p. 41. ISBN 978-0-9524387-5-5.
  40. ^ James, E. O. (1963). The Worship of the Sky-God: A Comparative Study in Semitic and Indo-European Religion. Jordan Lectures in Comparative Religion. London, England: University of London Press. pp. 24, 27f.
  41. ^ a b Lambert, W. G. (1964). «E. O. James: The worship of the Skygod: A comparative study in Semitic and Indo-European religion. (School of Oriental and African Studies, University of London. Jordan Lectures in Comparative Religion, vi.) viii, 175 pp. London: University of London, the Athlone Press, 1963. 25s». Bulletin of the School of Oriental and African Studies. London, England: University of London. 27 (1): 157–158. doi:10.1017/S0041977X00100345.
  42. ^ «Myths about the Milky Way». judy-volker.com. Retrieved March 21, 2022.
  43. ^ Leeming, David Adams (1998). Mythology: The Voyage of the Hero (Third ed.). Oxford, England: Oxford University Press. p. 44. ISBN 978-0-19-511957-2.
  44. ^ Pache, Corinne Ondine (2010). «Hercules». In Gargarin, Michael; Fantham, Elaine (eds.). Ancient Greece and Rome. Vol. 1: Academy-Bible. Oxford, England: Oxford University Press. p. 400. ISBN 978-0-19-538839-8.
  45. ^ Keith, W. J. (July 2007). «John Cowper Powys: Owen Glendower» (PDF). A Reader’s Companion. Archived (PDF) from the original on May 14, 2016. Retrieved October 11, 2019.
  46. ^ Harvey, Michael (2018). «Dreaming the Night Field: A Scenario for Storytelling Performance». Storytelling, Self, Society. 14 (1): 83–94. doi:10.13110/storselfsoci.14.1.0083. ISSN 1550-5340.
  47. ^ «Eryri — Snowdonia». snowdonia-npa.gov.uk. Retrieved May 5, 2022.
  48. ^ Harris, Mike (2011). Awen: The Quest of the Celtic Mysteries. Skylight Press. p. 144. ISBN 978-1-908011-36-7. The stars of the Corona Borealis, the Caer Arianrhod, as it is called in Welsh, whose shape is remembered in certain Bronze Age circles
  49. ^ Jankowski, Connie (2010). Pioneers of Light and Sound. Compass Point Books. p. 6. ISBN 978-0-7565-4306-8. Archived from the original on November 20, 2016.
  50. ^ Schiller, Jon (2010). Big Bang & Black Holes. CreateSpace. p. 163. ISBN 978-1-4528-6552-2. Archived from the original on November 20, 2016.
  51. ^ Simpson, John; Weiner, Edmund, eds. (March 30, 1989). The Oxford English Dictionary (2nd ed.). Oxford University Press. ISBN 978-0-19-861186-8. See the entries for «Milky Way» and «galaxy».
  52. ^ Eratosthenes (1997). Condos, Theony (ed.). Star Myths of the Greeks and Romans: A Sourcebook Containing the Constellations of Pseudo-Eratosthenes and the Poetic Astronomy of Hyginus. Red Wheel/Weiser. ISBN 978-1-890482-93-0. Archived from the original on November 20, 2016.
  53. ^ Pasachoff, Jay M. (1994). Astronomy: From the Earth to the Universe. Harcourt School. p. 500. ISBN 978-0-03-001667-7.
  54. ^ Rey, H. A. (1976). The Stars. Houghton Mifflin Harcourt. p. 145. ISBN 978-0-395-24830-0.
  55. ^ Pasachoff, Jay M.; Filippenko, Alex (2013). The Cosmos: Astronomy in the New Millennium. Cambridge University Press. p. 384. ISBN 978-1-107-68756-1.
  56. ^ Crossen, Craig (July 2013). «Observing the Milky Way, part I: Sagittarius & Scorpius». Sky & Telescope. 126 (1): 24. Bibcode:2013S&T…126a..24C.
  57. ^ Urton, Gary (1981). At the Crossroads of the Earth and the Sky: An Andean Cosmology. Latin American Monographs. Vol. 55. Austin: Univ. of Texas Pr. pp. 102–4, 109–11. ISBN 0-292-70349-X.
  58. ^ Starr, Michelle (July 14, 2020). «A Giant ‘Wall’ of Galaxies Has Been Found Stretching Across The Universe». ScienceAlert. Retrieved May 5, 2022.
  59. ^ Crumey, Andrew (2014). «Human contrast threshold and astronomical visibility». Monthly Notices of the Royal Astronomical Society. 442 (3): 2600–2619. arXiv:1405.4209. Bibcode:2014MNRAS.442.2600C. doi:10.1093/mnras/stu992. S2CID 119210885.
  60. ^ Steinicke, Wolfgang; Jakiel, Richard (2007). Galaxies and how to observe them. Astronomers’ observing guides. Springer. p. 94. ISBN 978-1-85233-752-0.
  61. ^ Falchi, Fabio; Cinzano, Pierantonio; Duriscoe, Dan; Kyba, Christopher C. M.; Elvidge, Christopher D.; Baugh, Kimberly; Portnov, Boris A.; Rybnikova, Nataliya A.; Furgoni, Riccardo (June 1, 2016). «The new world atlas of artificial night sky brightness». Science Advances. 2 (6): e1600377. arXiv:1609.01041. Bibcode:2016SciA….2E0377F. doi:10.1126/sciadv.1600377. ISSN 2375-2548. PMC 4928945. PMID 27386582.
  62. ^ Aristotle with W. D. Ross, ed., The Works of Aristotle … (Oxford, England: Clarendon Press, 1931), vol. III, Meteorologica, E. W. Webster, trans., Book 1, Part 8, pp. 39–40 Archived April 11, 2016, at the Wayback Machine : «(2) Anaxagoras, Democritus, and their schools say that the milky way is the light of certain stars … shaded by the earth from the sun’s rays.»
  63. ^ a b «What does your image show». mo-www.harvard.edu. Retrieved October 20, 2022.
  64. ^ a b Montada, Josep Puig (September 28, 2007). «Ibn Bajja». Stanford Encyclopedia of Philosophy. Archived from the original on July 28, 2012. Retrieved July 11, 2008.
  65. ^ Aristotle; Ross, W. D. (William David); Smith, J. A. (John Alexander) (1908–52). Works. Translated into English under the editorship of W.D. Ross. Robarts — University of Toronto. Oxford Clarendon Press.{{cite book}}: CS1 maint: date format (link)
  66. ^ Heidarzadeh, Tofigh (2008). A history of physical theories of comets, from Aristotle to Whipple. Springer. pp. 23–25. ISBN 978-1-4020-8322-8.
  67. ^ O’Connor, John J.; Robertson, Edmund F., «Abu Rayhan Muhammad ibn Ahmad al-Biruni», MacTutor History of Mathematics archive, University of St Andrews[unreliable source?]
  68. ^ Ragep, Jamil (1993). Nasir al-Din al-Tusi’s Memoir on Astronomy (al-Tadhkira fi ‘ilm al-hay’ a). New York: Springer-Verlag. p. 129.
  69. ^ Livingston, John W. (1971). «Ibn Qayyim al-Jawziyyah: A Fourteenth Century Defense against Astrological Divination and Alchemical Transmutation». Journal of the American Oriental Society. 91 (1): 96–103 [99]. doi:10.2307/600445. JSTOR 600445.
  70. ^ Galileo Galilei, Sidereus Nuncius (Venice, (Italy): Thomas Baglioni, 1610), pages 15 and 16. Archived March 16, 2016, at the Wayback Machine
    English translation: Galileo Galilei with Edward Stafford Carlos, trans., The Sidereal Messenger (London: Rivingtons, 1880), pages 42 and 43. Archived December 2, 2012, at the Wayback Machine
  71. ^ O’Connor, J. J.; Robertson, E. F. (November 2002). «Galileo Galilei». University of St. Andrews. Archived from the original on May 30, 2012. Retrieved January 8, 2007.
  72. ^ Thomas Wright, An Original Theory or New Hypothesis of the Universe … (London, England: H. Chapelle, 1750).
    • On page 57 Archived November 20, 2016, at the Wayback Machine, Wright stated that despite their mutual gravitational attraction, the stars in the constellations don’t collide because they are in orbit, so centrifugal force keeps them separated: » … centrifugal force, which not only preserves them in their orbits, but prevents them from rushing all together, by the common universal law of gravity, … «
    • On page 48 Archived November 20, 2016, at the Wayback Machine, Wright stated that the form of the Milky Way is a ring: » … the stars are not infinitely dispersed and distributed in a promiscuous manner throughout all the mundane space, without order or design, … this phænomenon [is] no other than a certain effect arising from the observer’s situation, … To a spectator placed in an indefinite space, … it [i.e. the Milky Way (Via Lactea)] [is] a vast ring of stars … «
    • On page 65 Archived November 20, 2016, at the Wayback Machine, Wright speculated that the central body of the Milky Way, around which the rest of the galaxy revolves, might not be visible to us: » … the central body A, being supposed as incognitum [i.e. an unknown], without [i.e. outside of] the finite view; … «
    • On page 73 Archived November 20, 2016, at the Wayback Machine, Wright called the Milky Way the Vortex Magnus (the great whirlpool) and estimated its diameter to be 8.64×1012 miles (13.9×1012 km).
    • On page 33 Archived November 20, 2016, at the Wayback Machine, Wright speculated that there are a vast number of inhabited planets in the galaxy: » … ; therefore we may justly suppose, that so many radiant bodies [i.e. stars] were not created barely to enlighten an infinite void, but to … display an infinite shapeless universe, crowded with myriads of glorious worlds, all variously revolving round them; and … with an inconceivable variety of beings and states, animate … «

  73. ^ Immanuel Kant, Allgemeine Naturgeschichte und Theorie des Himmels … Archived November 20, 2016, at the Wayback Machine [Universal Natural History and Theory of Heaven … ], (Koenigsberg and Leipzig, (Germany): Johann Friederich Petersen, 1755).
    On pages 2–3, Kant acknowledged his debt to Thomas Wright: «Dem Herrn Wright von Durham, einen Engeländer, war es vorbehalten, einen glücklichen Schritt zu einer Bemerkung zu thun, welche von ihm selber zu keiner gar zu tüchtigen Absicht gebraucht zu seyn scheinet, und deren nützliche Anwendung er nicht genugsam beobachtet hat. Er betrachtete die Fixsterne nicht als ein ungeordnetes und ohne Absicht zerstreutes Gewimmel, sondern er fand eine systematische Verfassung im Ganzen, und eine allgemeine Beziehung dieser Gestirne gegen einen Hauptplan der Raume, die sie einnehmen.» (To Mr. Wright of Durham, an Englishman, it was reserved to take a happy step towards an observation, which seemed, to him and to no one else, to be needed for a clever idea, the exploitation of which he hasn’t studied sufficiently. He regarded the fixed stars not as a disorganized swarm that was scattered without a design; rather, he found a systematic shape in the whole, and a general relation between these stars and the principal plane of the space that they occupy.)
  74. ^ Kant (1755), pages xxxiii–xxxvi of the Preface (Vorrede): Archived November 20, 2016, at the Wayback Machine «Ich betrachtete die Art neblichter Sterne, deren Herr von Maupertuis in der Abhandlung von der Figur der Gestirne gedenket, und die die Figur von mehr oder weniger offenen Ellipsen vorstellen, und versicherte mich leicht, daß sie nichts anders als eine Häufung vieler Fixsterne seyn können. Die jederzeit abgemessene Rundung dieser Figuren belehrte mich, daß hier ein unbegreiflich zahlreiches Sternenheer, und zwar um einen gemeinschaftlichen Mittelpunkt, müste geordnet seyn, weil sonst ihre freye Stellungen gegen einander, wohl irreguläre Gestalten, aber nicht abgemessene Figuren vorstellen würden. Ich sahe auch ein: daß sie in dem System, darinn sie sich vereinigt befinden, vornemlich auf eine Fläche beschränkt seyn müßten, weil sie nicht zirkelrunde, sondern elliptische Figuren abbilden, und daß sie wegen ihres blassen Lichts unbegreiflich weit von uns abstehen.» (I considered the type of nebulous stars, which Mr. de Maupertuis considered in his treatise on the shape of stars, and which present the figures of more or less open ellipses, and I readily assured myself, that they could be nothing else than a cluster of fixed stars. That these figures always measured round informed me that here an inconceivably numerous host of stars, [which were clustered] around a common center, must be orderly, because otherwise their free positions among each other would probably present irregular forms, not measurable figures. I also realized: that in the system in which they find themselves bound, they must be restricted primarily to a plane, because they display not circular, but elliptical figures, and that on account of their faint light, they are located inconceivably far from us.)
  75. ^ Evans, J. C. (November 24, 1998). «Our Galaxy». George Mason University. Archived from the original on June 30, 2012. Retrieved January 4, 2007.
  76. ^ The term Weltinsel (island universe) appears nowhere in Kant’s book of 1755. The term first appeared in 1850, in the third volume of von Humboldt’s Kosmos: Alexander von Humboldt, Kosmos, vol. 3 (Stuttgart & Tübingen, (Germany): J.G. Cotta, 1850), pp. 187, 189. From p. 187: Archived November 20, 2016, at the Wayback Machine «Thomas Wright von Durham, Kant, Lambert und zuerst auch William Herschel waren geneigt die Gestalt der Milchstraße und die scheinbare Anhäufung der Sterne in derselben als eine Folge der abgeplatteten Gestalt und ungleichen Dimensionen der Weltinsel (Sternschict) zu betrachten, in welche unser Sonnensystem eingeschlossen ist.» (Thomas Wright of Durham, Kant, Lambert and first of all also William Herschel were inclined to regard the shape of the Milky Way and the apparent clustering of stars in it as a consequence of the oblate shape and unequal dimensions of the world island (star stratum), in which our solar system is included.)
    In the English translation – Alexander von Humboldt with E.C. Otté, trans., Cosmos … (New York City: Harper & Brothers, 1897), vols. 3–5. see p. 147 Archived November 6, 2018, at the Wayback Machine.
  77. ^ William Herschel (1785) «On the Construction of the Heavens,» Philosophical Transactions of the Royal Society of London, 75 : 213–266. Herschel’s diagram of the Milky Way appears immediately after the article’s last page. See:
    • Google Books Archived November 20, 2016, at the Wayback Machine
    • The Royal Society of London Archived April 6, 2016, at the Wayback Machine

  78. ^ Abbey, Lenny. «The Earl of Rosse and the Leviathan of Parsontown». The Compleat Amateur Astronomer. Archived from the original on May 19, 2013. Retrieved January 4, 2007.
  79. ^ See:
    • Rosse revealed the spiral structure of Whirlpool Galaxy (M51) at the 1845 meeting of the British Association for the Advancement of Science. Rosse’s illustration of M51 was reproduced in J.P. Nichol’s book of 1846.
    • Rosse, Earl of (1846). «On the nebula 25 Herschel, or 61 [should read: 51] of Messier’s catalogue». Report of the Fifteenth Meeting of the British Association for the Advancement of Science; Held at Cambridge in June 1845 § Notices and Abstracts of Miscellaneous Communications to the Sections. Report of the … Meeting of the British Association for the Advancement of Science (1833): 4.
    • Nichol, John Pringle (1846). Thoughts on Some Important Points Relating to the System of the World. Edinburgh, Scotland: William Tait. p. 23. Rosse’s illustration of the Whirlpool Galaxy appears on the plate that immediately precedes p. 23.
    • South, James (1846). «Auszug aus einem Berichte über Lord Rosse’s grosses Telescop, den Sir James South in The Times, Nr. 18899, 1845 April 16 bekannt gemacht hat» [Excerpt from a report about Lord Rosse’s great telescope, which Sir James South made known in The Times [of London], no. 18,899, 1845 April 16]. Astronomische Nachrichten. 23 (536): 113–118. doi:10.1002/asna.18460230802. On March 5, 1845, Rosse observed M51, the Whirlpool Galaxy. From column 115: «The most popularly known nebulæ observed this night were the ring nebulæ in the Canes Venatici, or the 51st of Messier’s catalogue, which was resolved into stars with a magnifying power of 548; … «
    • Robinson, T. R. (1845). «On Lord Rosse’s telescope». Proceedings of the Royal Irish Academy. 3 (50): 114–133. Rosse’s early observations of nebulae and galaxies are discussed on pp. 127–130.
    • Rosse, The Earl of (1850). «Observations on the nebulae». Philosophical Transactions of the Royal Society of London. 140: 499–514. doi:10.1098/rstl.1850.0026. Rosse’s illustrations of nebulae and galaxies appear on the plates that immediately precede the article.
    • Bailey, M. E.; Butler, C.J.; McFarland, J. (April 2005). «Unwinding the discovery of spiral nebulae». Astronomy & Geophysics. 46 (2): 2.26–2.28. doi:10.1111/j.1468-4004.2005.46226.x.

  80. ^ See:
    • Kapteyn, Jacobus Cornelius (1906). «Statistical methods in stellar astronomy». In Rogers, Howard J. (ed.). Congress of Arts and Science, Universal Exposition, St. Louis, 1904. Vol. 4. Boston and New York: Houghton, Mifflin and Co. pp. 396–425. From pp. 419–420: «It follows that the one set of the stars must have a systematic motion relative to the other. … these two main directions of motion must be in reality diametrically opposite.»
    • Kapteyn, J.C. (1905). «Star streaming». Report of the Seventy-fifth Meeting of the British Association for the Advancement of Science, South Africa. Report of the … Meeting of the British Association for the Advancement of Science (1833): 257–265.

  81. ^ See:
    • Schwarzschild, K. (1907). «Ueber die Eigenbewegungen der Fixsterne» [On the proper motions of the fixed stars]. Nachrichten von der Königlichen Gesellschaft der Wissenschaften zu Göttingen (Reports of the Royal Society of Science at Göttingen) (in German). 5: 614–632. Bibcode:1907NWGot…5..614S.
    • Schwarzschild, K. (1908). «Ueber die Bestimmung von Vertex und Apex nach der Ellipsoidhypothese aus einer geringeren Anzahl beobachteter Eigenbewegungen» [On the determination, according to the ellipsoid hypothesis, of the vertex and apex from a small number of observed proper motions]. Nachrichten von der Königlichen Gesellschaft der Wissenschaften zu Göttingen (in German): 191–200.

  82. ^ Curtis, Heber D. (1917). «Novae in spiral nebulae and the island universe theory». Publications of the Astronomical Society of the Pacific. 29 (171): 206–207. Bibcode:1917PASP…29..206C. doi:10.1086/122632.
  83. ^ Curtis, H. D. (1988). «Novae in spiral nebulae and the Island Universe Theory». Publications of the Astronomical Society of the Pacific. 100: 6–7. Bibcode:1988PASP..100….6C. doi:10.1086/132128.
  84. ^ Weaver, Harold F. «Robert Julius Trumpler». National Academy of Sciences. Archived from the original on June 4, 2012. Retrieved January 5, 2007.
  85. ^ Sandage, Allan (1989). «Edwin Hubble, 1889–1953». Journal of the Royal Astronomical Society of Canada. 83 (6): 351. Bibcode:1989JRASC..83..351S.
  86. ^ Hubble, E. P. (1929). «A spiral nebula as a stellar system, Messier 31». The Astrophysical Journal. 69: 103–158. Bibcode:1929ApJ….69..103H. doi:10.1086/143167.
  87. ^ «New Milky Way Map Is a Spectacular Billion-Star Atlas». September 14, 2016. Archived from the original on September 15, 2016. Retrieved September 15, 2016.
  88. ^ «Gaia > Gaia DR1». www.cosmos.esa.int. Archived from the original on September 15, 2016. Retrieved September 15, 2016.
  89. ^ Skibba, Ramin (June 10, 2021). «A galactic archaeologist digs into the Milky Way’s history». Knowable Magazine. doi:10.1146/knowable-060921-1. S2CID 236290725. Retrieved August 4, 2022.
  90. ^ Poggio, E.; Drimmel, R.; Andrae, R.; Bailer-Jones, C. A. L.; Fouesneau, M.; Lattanzi, M. G.; Smart, R. L.; Spagna, A. (2020). «Evidence of a dynamically evolving Galactic warp». Nature Astronomy. 4 (6): 590–596. arXiv:1912.10471. Bibcode:2020NatAs…4..590P. doi:10.1038/s41550-020-1017-3. S2CID 209444772.
  91. ^ a b Alves, João; Zucker, Catherine; Goodman, Alyssa A.; Speagle, Joshua S.; Meingast, Stefan; Robitaille, Thomas; Finkbeiner, Douglas P.; Schlafly, Edward F.; Green, Gregory M. (January 7, 2020). «A Galactic-scale gas wave in the Solar Neighborhood». Nature. 578 (7794): 237–239. arXiv:2001.08748. Bibcode:2020Natur.578..237A. doi:10.1038/s41586-019-1874-z. PMID 31910431. S2CID 210086520.
  92. ^ a b Boehle, A.; Ghez, A. M.; Schödel, R.; Meyer, L.; Yelda, S.; Albers, S.; Martinez, G. D.; Becklin, E. E.; Do, T.; Lu, J. R.; Matthews, K.; Morris, M. R.; Sitarski, B.; Witzel, G. (October 3, 2016). «An Improved Distance and Mass Estimate for SGR A* from a Multistar Orbit Analysis» (PDF). The Astrophysical Journal. 830 (1): 17. arXiv:1607.05726. Bibcode:2016ApJ…830…17B. doi:10.3847/0004-637X/830/1/17. hdl:10261/147803. S2CID 307657. Archived (PDF) from the original on December 2, 2017. Retrieved July 31, 2018.
  93. ^ Majaess, D. J.; Turner, D. G.; Lane, D. J. (2009). «Characteristics of the Galaxy according to Cepheids». Monthly Notices of the Royal Astronomical Society. 398 (1): 263–270. arXiv:0903.4206. Bibcode:2009MNRAS.398..263M. doi:10.1111/j.1365-2966.2009.15096.x. S2CID 14316644.
  94. ^ English, Jayanne (January 14, 2000). «Exposing the Stuff Between the Stars». Hubble News Desk. Archived from the original on July 7, 2007. Retrieved May 10, 2007.
  95. ^ Mullen, Leslie (May 18, 2001). «Galactic Habitable Zones». NAI Features Archive. Nasa Astrobiology Institute. Archived from the original on April 9, 2013. Retrieved May 9, 2013.
  96. ^ Sundin, M. (2006). «The galactic habitable zone in barred galaxies». International Journal of Astrobiology. 5 (4): 325–326. Bibcode:2006IJAsB…5..325S. doi:10.1017/S1473550406003065. S2CID 122018103.
  97. ^ «Magnitude». National Solar Observatory – Sacramento Peak. Archived from the original on February 6, 2008. Retrieved August 9, 2013.
  98. ^ Moore, Patrick; Rees, Robin (2014). Patrick Moore’s Data Book of Astronomy (2nd ed.). Cambridge University Press. p. 4. ISBN 978-1-139-49522-6. Archived from the original on February 15, 2017.
  99. ^ Gillman, M.; Erenler, H. (2008). «The galactic cycle of extinction» (PDF). International Journal of Astrobiology. 7 (1): 17. Bibcode:2008IJAsB…7…17G. CiteSeerX 10.1.1.384.9224. doi:10.1017/S1473550408004047. S2CID 31391193. Archived (PDF) from the original on June 1, 2019. Retrieved July 31, 2018.
  100. ^ Overholt, A. C.; Melott, A. L.; Pohl, M. (2009). «Testing the link between terrestrial climate change and galactic spiral arm transit». The Astrophysical Journal. 705 (2): L101–L103. arXiv:0906.2777. Bibcode:2009ApJ…705L.101O. doi:10.1088/0004-637X/705/2/L101. S2CID 734824.
  101. ^ a b Sparke, Linda S.; Gallagher, John S. (2007). Galaxies in the Universe: An Introduction. p. 90. ISBN 978-1-139-46238-9.
  102. ^ Garlick, Mark Antony (2002). The Story of the Solar System. Cambridge University. p. 46. ISBN 978-0-521-80336-6.
  103. ^ «Solar System’s ‘Nose’ Found; Aimed at Constellation Scorpius». April 8, 2011. Archived from the original on September 7, 2015.
  104. ^ Blaauw, A.; et al. (1960), «The new I. A. U. system of galactic coordinates (1958 revision)», Monthly Notices of the Royal Astronomical Society, 121 (2): 123–131, Bibcode:1960MNRAS.121..123B, doi:10.1093/mnras/121.2.123
  105. ^ a b Wilson, Thomas L.; et al. (2009), Tools of Radio Astronomy, Springer Science & Business Media, ISBN 978-3-540-85121-9, archived from the original on April 26, 2016
  106. ^ a b Kiss, Cs; Moór, A.; Tóth, L. V. (April 2004). «Far-infrared loops in the 2nd Galactic Quadrant». Astronomy and Astrophysics. 418: 131–141. arXiv:astro-ph/0401303. Bibcode:2004A&A…418..131K. doi:10.1051/0004-6361:20034530. S2CID 7825138.
  107. ^ a b Lampton, M., Lieu, R.; et al. (February 1997). «An All-Sky Catalog of Faint Extreme Ultraviolet Sources». The Astrophysical Journal Supplement Series. 108 (2): 545–557. Bibcode:1997ApJS..108..545L. doi:10.1086/312965.
  108. ^ van Woerden, Hugo; Strom, Richard G. (June 2006). «The beginnings of radio astronomy in the Netherlands» (PDF). Journal of Astronomical History and Heritage. 9 (1): 3–20. Bibcode:2006JAHH….9….3V. Archived from the original (PDF) on September 19, 2010.
  109. ^ a b c López-Corredoira, M.; Allende Prieto, C.; Garzón, F.; Wang, H.; Liu, C.; Deng, L. (April 9, 2018). «Disk stars in the Milky Way detected beyond 25 KPC from its center». Astronomy & Astrophysics. 612: L8. arXiv:1804.03064. Bibcode:2018A&A…612L…8L. doi:10.1051/0004-6361/201832880. S2CID 59933365.
  110. ^ a b Sale, S. E.; et al. (2010). «The structure of the outer Galactic disc as revealed by IPHAS early A stars». Monthly Notices of the Royal Astronomical Society. 402 (2): 713–723. arXiv:0909.3857. Bibcode:2010MNRAS.402..713S. doi:10.1111/j.1365-2966.2009.15746.x. S2CID 12884630.
  111. ^ https://ned.ipac.caltech.edu/level5/PROPERTIES/dog.html[bare URL]
  112. ^ Goodwin, S. P.; Gribbin, J.; Hendry, M. A. (April 22, 1997). «The Milky Way is just an average spiral». arXiv:astro-ph/9704216.
  113. ^ Castro-Rodríguez, N.; López-Corredoira, M.; Sánchez-Saavedra, M. L.; Battaner, E. (2002). «Warps and correlations with intrinsic parameters of galaxies in the visible and radio». Astronomy & Astrophysics. 391 (2): 519–530. arXiv:astro-ph/0205553. Bibcode:2002A&A…391..519C. doi:10.1051/0004-6361:20020895. S2CID 17813024.
  114. ^ Goodwin, S. P.; Gribbin, J.; Hendry, M. A. (April 30, 1997). «New Determination of the Hubble Parameter Using the Principle of Terrestrial Mediocrity». arXiv:astro-ph/9704289.
  115. ^ «How Big is Our Universe: How far is it across the Milky Way?». NASA-Smithsonian Education Forum on the Structure and Evolution of the Universe, at the Harvard Smithsonian Center for Astrophysics. Archived from the original on March 5, 2013. Retrieved March 13, 2013.
  116. ^ Newberg, Heidi Jo; et al. (March 1, 2015). «Rings and Radial Waves in the Disk of the Milky Way». The Astrophysical Journal. 801 (2): 105. arXiv:1503.00257. Bibcode:2015ApJ…801..105X. doi:10.1088/0004-637X/801/2/105. S2CID 119124338.
  117. ^ Mary L. Martialay (March 11, 2015). «The Corrugated Galaxy – Milky Way May Be Much Larger Than Previously Estimated» (Press release). Rensselaer Polytechnic Institute. Archived from the original on March 13, 2015.
  118. ^ Sheffield, Allyson A.; Price-Whelan, Adrian M.; Tzanidakis, Anastasios; Johnston, Kathryn V.; Laporte, Chervin F. P.; Sesar, Branimir (2018). «A Disk Origin for the Monoceros Ring and A13 Stellar Overdensities». The Astrophysical Journal. 854 (1): 47. arXiv:1801.01171. Bibcode:2018ApJ…854…47S. doi:10.3847/1538-4357/aaa4b6. S2CID 118932403.
  119. ^ David Freeman (May 25, 2018). «The Milky Way galaxy may be much bigger than we thought» (Press release). CNBC. Archived from the original on August 13, 2018. Retrieved August 13, 2018.
  120. ^ July 2018, Elizabeth Howell 02 (July 2, 2018). «It Would Take 200,000 Years at Light Speed to Cross the Milky Way». Space.com.
  121. ^ Coffey, Jeffrey. «How big is the Milky Way?». Universe Today. Archived from the original on September 24, 2013. Retrieved November 28, 2007.
  122. ^ Rix, Hans-Walter; Bovy, Jo (2013). «The Milky Way’s Stellar Disk». The Astronomy and Astrophysics Review. 21: 61. arXiv:1301.3168. Bibcode:2013A&ARv..21…61R. doi:10.1007/s00159-013-0061-8. S2CID 117112561.
  123. ^ Kafle, P.R.; Sharma, S.; Lewis, G.F.; Bland-Hawthorn, J. (2012). «Kinematics of the Stellar Halo and the Mass Distribution of the Milky Way Using Blue Horizontal Branch Stars». The Astrophysical Journal. 761 (2): 17. arXiv:1210.7527. Bibcode:2012ApJ…761…98K. doi:10.1088/0004-637X/761/2/98. S2CID 119303111.
  124. ^ Karachentsev, I. D.; Kashibadze, O. G. (2006). «Masses of the local group and of the M81 group estimated from distortions in the local velocity field». Astrophysics. 49 (1): 3–18. Bibcode:2006Ap…..49….3K. doi:10.1007/s10511-006-0002-6. S2CID 120973010.
  125. ^ Vayntrub, Alina (2000). «Mass of the Milky Way». The Physics Factbook. Archived from the original on August 13, 2014. Retrieved May 9, 2007.
  126. ^ Battaglia, G.; et al. (2005). «The radial velocity dispersion profile of the Galactic halo: Constraining the density profile of the dark halo of the Milky Way». Monthly Notices of the Royal Astronomical Society. 364 (2): 433–442. arXiv:astro-ph/0506102. Bibcode:2005MNRAS.364..433B. doi:10.1111/j.1365-2966.2005.09367.x. S2CID 15562509.
  127. ^ Finley, Dave; Aguilar, David (January 5, 2009). «Milky Way a Swifter Spinner, More Massive, New Measurements Show» (Press release). National Radio Astronomy Observatory. Archived from the original on August 8, 2014. Retrieved January 20, 2009.
  128. ^ Reid, M. J.; et al. (2009). «Trigonometric parallaxes of massive star-forming regions. VI. Galactic structure, fundamental parameters, and noncircular motions». The Astrophysical Journal. 700 (1): 137–148. arXiv:0902.3913. Bibcode:2009ApJ…700..137R. doi:10.1088/0004-637X/700/1/137. S2CID 11347166.
  129. ^ Gnedin, O. Y.; et al. (2010). «The mass profile of the Galaxy to 80 kpc». The Astrophysical Journal. 720 (1): L108–L112. arXiv:1005.2619. Bibcode:2010ApJ…720L.108G. doi:10.1088/2041-8205/720/1/L108. S2CID 119245657.
  130. ^ a b Peñarrubia, Jorge; et al. (2014). «A dynamical model of the local cosmic expansion». Monthly Notices of the Royal Astronomical Society. 433 (3): 2204–2222. arXiv:1405.0306. Bibcode:2014MNRAS.443.2204P. doi:10.1093/mnras/stu879. S2CID 119295582.
  131. ^ Grand, Robert J J.; Deason, Alis J.; White, Simon D M.; Simpson, Christine M.; Gómez, Facundo A.; Marinacci, Federico; Pakmor, Rüdiger (2019). «The effects of dynamical substructure on Milky Way mass estimates from the high-velocity tail of the local stellar halo». Monthly Notices of the Royal Astronomical Society: Letters. 487 (1): L72–L76. arXiv:1905.09834. Bibcode:2019MNRAS.487L..72G. doi:10.1093/mnrasl/slz092. S2CID 165163524.
  132. ^ a b McMillan, P. J. (July 2011). «Mass models of the Milky Way». Monthly Notices of the Royal Astronomical Society. 414 (3): 2446–2457. arXiv:1102.4340. Bibcode:2011MNRAS.414.2446M. doi:10.1111/j.1365-2966.2011.18564.x. S2CID 119100616.
  133. ^ McMillan, Paul J. (February 11, 2017). «The mass distribution and gravitational potential of the Milky Way». Monthly Notices of the Royal Astronomical Society. 465 (1): 76–94. arXiv:1608.00971. Bibcode:2017MNRAS.465…76M. doi:10.1093/mnras/stw2759. S2CID 119183093.
  134. ^ Slobodan Ninković (April 2017). «Mass Distribution and Gravitational Potential of the Milky Way». Open Astronomy. 26 (1): 1–6. Bibcode:2017OAst…26….1N. doi:10.1515/astro-2017-0002.
  135. ^ Phelps, Steven; et al. (October 2013). «The Mass of the Milky Way and M31 Using the Method of Least Action». The Astrophysical Journal. 775 (2): 102–113. arXiv:1306.4013. Bibcode:2013ApJ…775..102P. doi:10.1088/0004-637X/775/2/102. S2CID 21656852. 102.
  136. ^ Kafle, Prajwal Raj; et al. (October 2014). «On the Shoulders of Giants: Properties of the Stellar Halo and the Milky Way Mass Distribution». The Astrophysical Journal. 794 (1): 17. arXiv:1408.1787. Bibcode:2014ApJ…794…59K. doi:10.1088/0004-637X/794/1/59. S2CID 119040135. 59.
  137. ^ Licquia, Timothy; Newman, J. (2013). «Improved Constraints on the Total Stellar Mass, Color, and Luminosity of the Milky Way». American Astronomical Society, AAS Meeting #221, #254.11. 221: 254.11. Bibcode:2013AAS…22125411L.
  138. ^ a b c «The Interstellar Medium». Archived from the original on April 19, 2015. Retrieved May 2, 2015.
  139. ^ a b «Lecture Seven: The Milky Way: Gas» (PDF). Archived from the original (PDF) on July 8, 2015. Retrieved May 2, 2015.
  140. ^ Villard, Ray (January 11, 2012). «The Milky Way Contains at Least 100 Billion Planets According to Survey». HubbleSite.org. Archived from the original on July 23, 2014. Retrieved January 11, 2012.
  141. ^ Young, Kelly (June 6, 2006). «Andromeda Galaxy hosts a trillion stars». New Scientist. Archived from the original on January 5, 2011. Retrieved June 8, 2006.
  142. ^ Napiwotzki, R. (2009). The galactic population of white dwarfs. In Journal of Physics: Conference Series (Vol. 172, No. 1, p. 012004). IOP Publishing.
  143. ^ «NASA – Neutron Stars». NASA. Archived from the original on September 8, 2018. Retrieved April 5, 2018.
  144. ^ a b Levine, E. S.; Blitz, L.; Heiles, C. (2006). «The spiral structure of the outer Milky Way in hydrogen». Science. 312 (5781): 1773–1777. arXiv:astro-ph/0605728. Bibcode:2006Sci…312.1773L. doi:10.1126/science.1128455. PMID 16741076. S2CID 12763199.
  145. ^ Dickey, J. M.; Lockman, F. J. (1990). «H I in the Galaxy». Annual Review of Astronomy and Astrophysics. 28: 215–259. Bibcode:1990ARA&A..28..215D. doi:10.1146/annurev.aa.28.090190.001243.
  146. ^ Savage, B. D.; Wakker, B. P. (2009). «The extension of the transition temperature plasma into the lower galactic halo». The Astrophysical Journal. 702 (2): 1472–1489. arXiv:0907.4955. Bibcode:2009ApJ…702.1472S. doi:10.1088/0004-637X/702/2/1472. S2CID 119245570.
  147. ^ Connors, Tim W.; Kawata, Daisuke; Gibson, Brad K. (2006). «N-body simulations of the Magellanic stream». Monthly Notices of the Royal Astronomical Society. 371 (1): 108–120. arXiv:astro-ph/0508390. Bibcode:2006MNRAS.371..108C. doi:10.1111/j.1365-2966.2006.10659.x. S2CID 15563258.
  148. ^ Coffey, Jerry (May 11, 2017). «Absolute Magnitude». Archived from the original on September 13, 2011.
  149. ^ Karachentsev, Igor D.; Karachentseva, Valentina E.; Huchtmeier, Walter K.; Makarov, Dmitry I. (2003). «A Catalog of Neighboring Galaxies». The Astronomical Journal. 127 (4): 2031–2068. Bibcode:2004AJ….127.2031K. doi:10.1086/382905.
  150. ^ Borenstein, Seth (February 19, 2011). «Cosmic census finds crowd of planets in our galaxy». The Washington Post. Associated Press. Archived from the original on February 22, 2011.
  151. ^ Sumi, T.; et al. (2011). «Unbound or distant planetary mass population detected by gravitational microlensing». Nature. 473 (7347): 349–352. arXiv:1105.3544. Bibcode:2011Natur.473..349S. doi:10.1038/nature10092. PMID 21593867. S2CID 4422627.
  152. ^ «Free-Floating Planets May be More Common Than Stars». Pasadena, CA: NASA’s Jet Propulsion Laboratory. February 18, 2011. Archived from the original on May 22, 2011. The team estimates there are about twice as many of them as stars.
  153. ^ Staff (January 7, 2013). «17 Billion Earth-Size Alien Planets Inhabit Milky Way». Space.com. Archived from the original on October 6, 2014. Retrieved January 8, 2013.
  154. ^ Overbye, Dennis (November 4, 2013). «Far-Off Planets Like the Earth Dot the Galaxy». New York Times. Archived from the original on November 5, 2013. Retrieved November 5, 2013.
  155. ^ Petigura, Eric A.; Howard, Andrew W.; Marcy, Geoffrey W. (October 31, 2013). «Prevalence of Earth-size planets orbiting Sun-like stars». Proceedings of the National Academy of Sciences of the United States of America. 110 (48): 19273–19278. arXiv:1311.6806. Bibcode:2013PNAS..11019273P. doi:10.1073/pnas.1319909110. PMC 3845182. PMID 24191033.
  156. ^ Borenstein, Seth (November 4, 2013). «Milky Way Teeming With Billions Of Earth-Size Planets». The Associated Press. The Huffington Post. Archived from the original on November 4, 2014.
  157. ^ Khan, Amina (November 4, 2013). «Milky Way may host billions of Earth-size planets». Los Angeles Times. Archived from the original on November 6, 2013. Retrieved November 5, 2013.
  158. ^ Anglada-Escudé, Guillem; Amado, Pedro J.; Barnes, John; et al. (2016). «A terrestrial planet candidate in a temperate orbit around Proxima Centauri». Nature. 536 (7617): 437–440. arXiv:1609.03449. Bibcode:2016Natur.536..437A. doi:10.1038/nature19106. PMID 27558064. S2CID 4451513.
  159. ^ Staff (January 7, 2013). «‘Exocomets’ Common Across Milky Way Galaxy». Space.com. Archived from the original on September 16, 2014. Retrieved January 8, 2013.
  160. ^ Overbye, Dennis (November 5, 2020). «Looking for Another Earth? Here Are 300 Million, Maybe – A new analysis of data from NASA’s Kepler spacecraft increases the number of habitable exoplanets thought to exist in this galaxy». The New York Times. Archived from the original on November 5, 2020. Retrieved November 5, 2020.
  161. ^ a b Chou, Felicia; Anderson, Janet; Watzke, Megan (January 5, 2015). «Release 15-001 – NASA’s Chandra Detects Record-Breaking Outburst from Milky Way’s Black Hole». NASA. Archived from the original on January 6, 2015. Retrieved January 6, 2015.
  162. ^ «The Milky Way is warped». phys.org. Archived from the original on February 7, 2019. Retrieved February 22, 2019.
  163. ^ Chen, Xiaodian; Wang, Shu; Deng, Licai; de Grijs, Richard; Liu, Chao; Tian, Hao (February 4, 2019). «An intuitive 3D map of the Galactic warp’s precession traced by classical Cepheids». Nature Astronomy. 3 (4): 320–325. arXiv:1902.00998. Bibcode:2019NatAs…3..320C. doi:10.1038/s41550-018-0686-7. ISSN 2397-3366. S2CID 119290364.
  164. ^ Gerard de Vaucouleurs (1964), Interpretation of velocity distribution of the inner regions of the Galaxy Archived February 3, 2019, at the Wayback Machine
  165. ^ Peters, W.L. III. (1975), Models for the inner regions of the Galaxy. I Archived February 3, 2019, at the Wayback Machine
  166. ^ Hammersley, P. L.; Garzon, F.; Mahoney, T.; Calbet, X. (1994), Infrared Signatures of the Inner Spiral Arms and Bar Archived February 3, 2019, at the Wayback Machine
  167. ^ McKee, Maggie (August 16, 2005). «Bar at Milky Way’s heart revealed». New Scientist. Archived from the original on October 9, 2014. Retrieved June 17, 2009.
  168. ^ a b Gillessen, S.; et al. (2009). «Monitoring stellar orbits around the massive black hole in the Galactic Center». Astrophysical Journal. 692 (2): 1075–1109. arXiv:0810.4674. Bibcode:2009ApJ…692.1075G. doi:10.1088/0004-637X/692/2/1075. S2CID 1431308.
  169. ^ Reid, M. J.; et al. (November 2009). «A trigonometric parallax of Sgr B2». The Astrophysical Journal. 705 (2): 1548–1553. arXiv:0908.3637. Bibcode:2009ApJ…705.1548R. doi:10.1088/0004-637X/705/2/1548. S2CID 1916267.
  170. ^ a b Vanhollebeke, E.; Groenewegen, M. A. T.; Girardi, L. (April 2009). «Stellar populations in the Galactic bulge. Modelling the Galactic bulge with TRILEGAL». Astronomy and Astrophysics. 498 (1): 95–107. arXiv:0903.0946. Bibcode:2009A&A…498…95V. doi:10.1051/0004-6361/20078472.
  171. ^ a b c d Majaess, D. (March 2010). «Concerning the Distance to the Center of the Milky Way and Its Structure». Acta Astronomica. 60 (1): 55. arXiv:1002.2743. Bibcode:2010AcA….60…55M.
  172. ^ Grant, J.; Lin, B. (2000). «The Stars of the Milky Way». Fairfax Public Access Corporation. Archived from the original on June 11, 2007. Retrieved May 9, 2007.
  173. ^ Shen, J.; Rich, R. M.; Kormendy, J.; Howard, C. D.; De Propris, R.; Kunder, A. (2010). «Our Milky Way As a Pure-Disk Galaxy – A Challenge for Galaxy Formation». The Astrophysical Journal. 720 (1): L72–L76. arXiv:1005.0385. Bibcode:2010ApJ…720L..72S. doi:10.1088/2041-8205/720/1/L72. S2CID 118470423.
  174. ^ Ciambur, Bogdan C.; Graham, Alister W.; Bland-Hawthorn, Joss (2017). «Quantifying the (X/peanut)-shaped structure of the Milky Way – new constraints on the bar geometry». Monthly Notices of the Royal Astronomical Society. 471 (4): 3988. arXiv:1706.09902. Bibcode:2017MNRAS.471.3988C. doi:10.1093/mnras/stx1823. S2CID 119376558.
  175. ^ Jones, Mark H.; Lambourne, Robert J.; Adams, David John (2004). An Introduction to Galaxies and Cosmology. Cambridge University Press. pp. 50–51. ISBN 978-0-521-54623-2.
  176. ^ a b Ghez, A. M.; et al. (December 2008). «Measuring distance and properties of the Milky Way’s central supermassive black hole with stellar orbits». The Astrophysical Journal. 689 (2): 1044–1062. arXiv:0808.2870. Bibcode:2008ApJ…689.1044G. doi:10.1086/592738. S2CID 18335611.
  177. ^ a b Wang, Q.D.; Nowak, M.A.; Markoff, S.B.; Baganoff, F.K.; Nayakshin, S.; Yuan, F.; Cuadra, J.; Davis, J.; Dexter, J.; Fabian, A.C.; Grosso, N.; Haggard, D.; Houck, J.; Ji, L.; Li, Z.; Neilsen, J.; Porquet, D.; Ripple, F.; Shcherbakov, R.V. (2013). «Dissecting X-ray-Emitting Gas Around the Center of Our Galaxy». Science. 341 (6149): 981–983. arXiv:1307.5845. Bibcode:2013Sci…341..981W. doi:10.1126/science.1240755. PMID 23990554. S2CID 206550019.
  178. ^ Blandford, R. D. (August 8–12, 1998). Origin and Evolution of Massive Black Holes in Galactic Nuclei. Galaxy Dynamics, proceedings of a conference held at Rutgers University, ASP Conference Series. Vol. 182. Rutgers University (published August 1999). arXiv:astro-ph/9906025. Bibcode:1999ASPC..182…87B.
  179. ^ Frolov, Valeri P.; Zelnikov, Andrei (2011). Introduction to Black Hole Physics. Oxford University Press. pp. 11, 36. ISBN 978-0-19-969229-3. Archived from the original on August 10, 2016.
  180. ^ Cabrera-Lavers, A.; et al. (December 2008). «The long Galactic bar as seen by UKIDSS Galactic plane survey». Astronomy and Astrophysics. 491 (3): 781–787. arXiv:0809.3174. Bibcode:2008A&A…491..781C. doi:10.1051/0004-6361:200810720. S2CID 15040792.
  181. ^ Nishiyama, S.; et al. (2005). «A distinct structure inside the Galactic bar». The Astrophysical Journal. 621 (2): L105. arXiv:astro-ph/0502058. Bibcode:2005ApJ…621L.105N. doi:10.1086/429291. S2CID 399710.
  182. ^ Alcock, C.; et al. (1998). «The RR Lyrae population of the Galactic Bulge from the MACHO database: mean colors and magnitudes». The Astrophysical Journal. 492 (2): 190–199. Bibcode:1998ApJ…492..190A. doi:10.1086/305017.
  183. ^ Kunder, A.; Chaboyer, B. (2008). «Metallicity analysis of Macho Galactic Bulge RR0 Lyrae stars from their light curves». The Astronomical Journal. 136 (6): 2441–2452. arXiv:0809.1645. Bibcode:2008AJ….136.2441K. doi:10.1088/0004-6256/136/6/2441. S2CID 16046532.
  184. ^ Staff (September 12, 2005). «Introduction: Galactic Ring Survey». Boston University. Archived from the original on July 13, 2007. Retrieved May 10, 2007.
  185. ^ Bhat, C. L.; Kifune, T.; Wolfendale, A. W. (November 21, 1985). «A cosmic-ray explanation of the galactic ridge of cosmic X-rays». Nature. 318 (6043): 267–269. Bibcode:1985Natur.318..267B. doi:10.1038/318267a0. S2CID 4262045.
  186. ^ Georg Weidenspointner; et al. (January 10, 2008). «An asymmetric distribution of positrons in the Galactic disk revealed by γ-rays». Nature. 451 (7175): 159–162. Bibcode:2008Natur.451..159W. doi:10.1038/nature06490. PMID 18185581. S2CID 4333175.
  187. ^ a b «NASA – Satellite Explains Giant Cloud of Antimatter». www.nasa.gov. January 9, 2008. Retrieved July 2, 2021.
  188. ^ «Antimatter Clouds and Fountains – NASA Press Release 97-83». heasarc.gsfc.nasa.gov. Retrieved July 2, 2021.
  189. ^ Overbye, Dennis (November 9, 2010). «Bubbles of Energy Are Found in Galaxy». The New York Times. Archived from the original on January 10, 2016.
  190. ^ «NASA’s Fermi Telescope Finds Giant Structure in our Galaxyl». NASA. Archived from the original on August 23, 2014. Retrieved November 10, 2010.
  191. ^ Carretti, E.; Crocker, R. M.; Staveley-Smith, L.; Haverkorn, M.; Purcell, C.; Gaensler, B. M.; Bernardi, G.; Kesteven, M. J.; Poppi, S. (2013). «Giant magnetized outflows from the centre of the Milky Way». Nature. 493 (7430): 66–69. arXiv:1301.0512. Bibcode:2013Natur.493…66C. doi:10.1038/nature11734. PMID 23282363. S2CID 4426371.
  192. ^ Churchwell, E.; et al. (2009). «The Spitzer/GLIMPSE surveys: a new view of the Milky Way». Publications of the Astronomical Society of the Pacific. 121 (877): 213–230. Bibcode:2009PASP..121..213C. doi:10.1086/597811. S2CID 15529740.
  193. ^ Taylor, J. H.; Cordes, J. M. (1993). «Pulsar distances and the galactic distribution of free electrons». The Astrophysical Journal. 411: 674. Bibcode:1993ApJ…411..674T. doi:10.1086/172870.
  194. ^ a b c Russeil, D. (2003). «Star-forming complexes and the spiral structure of our Galaxy». Astronomy and Astrophysics. 397: 133–146. Bibcode:2003A&A…397..133R. doi:10.1051/0004-6361:20021504.
  195. ^ Dame, T. M.; Hartmann, D.; Thaddeus, P. (2001). «The Milky Way in molecular clouds: A new complete CO survey». The Astrophysical Journal. 547 (2): 792–813. arXiv:astro-ph/0009217. Bibcode:2001ApJ…547..792D. doi:10.1086/318388. S2CID 118888462.
  196. ^ a b c Benjamin, R. A. (2008). Beuther, H.; Linz, H.; Henning, T. (eds.). The Spiral Structure of the Galaxy: Something Old, Something New... Massive Star Formation: Observations Confront Theory. Vol. 387. Astronomical Society of the Pacific Conference Series. p. 375. Bibcode:2008ASPC..387..375B.
    See also Bryner, Jeanna (June 3, 2008). «New Images: Milky Way Loses Two Arms». Space.com. Archived from the original on June 4, 2008. Retrieved June 4, 2008.
  197. ^ a b c Majaess, D. J.; Turner, D. G.; Lane, D. J. (2009). «Searching Beyond the Obscuring Dust Between the Cygnus-Aquila Rifts for Cepheid Tracers of the Galaxy’s Spiral Arms». The Journal of the American Association of Variable Star Observers. 37 (2): 179. arXiv:0909.0897. Bibcode:2009JAVSO..37..179M.
  198. ^ Lépine, J. R. D.; et al. (2011). «The spiral structure of the Galaxy revealed by CS sources and evidence for the 4:1 resonance». Monthly Notices of the Royal Astronomical Society. 414 (2): 1607–1616. arXiv:1010.1790. Bibcode:2011MNRAS.414.1607L. doi:10.1111/j.1365-2966.2011.18492.x. S2CID 118477787.
  199. ^ a b Drimmel, R. (2000). «Evidence for a two-armed spiral in the Milky Way». Astronomy & Astrophysics. 358: L13–L16. arXiv:astro-ph/0005241. Bibcode:2000A&A…358L..13D.
  200. ^ Sanna, A.; Reid, M. J.; Dame, T. M.; Menten, K. M.; Brunthaler, A. (2017). «Mapping spiral structure on the far side of the Milky Way». Science. 358 (6360): 227–230. arXiv:1710.06489. Bibcode:2017Sci…358..227S. doi:10.1126/science.aan5452. PMID 29026043. S2CID 206660521.
  201. ^ a b McClure-Griffiths, N. M.; Dickey, J. M.; Gaensler, B. M.; Green, A. J. (2004). «A Distant Extended Spiral Arm in the Fourth Quadrant of the Milky Way». The Astrophysical Journal. 607 (2): L127. arXiv:astro-ph/0404448. Bibcode:2004ApJ…607L.127M. doi:10.1086/422031. S2CID 119327129.
  202. ^ Benjamin, R. A.; et al. (2005). «First GLIMPSE results on the stellar structure of the Galaxy». The Astrophysical Journal. 630 (2): L149–L152. arXiv:astro-ph/0508325. Bibcode:2005ApJ…630L.149B. doi:10.1086/491785. S2CID 14782284.
  203. ^ «Massive stars mark out Milky Way’s ‘missing’ arms» (Press release). Leeds, UK: University of Leeds. December 17, 2013. Archived from the original on December 18, 2013. Retrieved December 18, 2013.
  204. ^ Westerholm, Russell (December 18, 2013). «Milky Way Galaxy has four arms, reaffirming old data and contradicting recent research». University Herald. Archived from the original on December 19, 2013. Retrieved December 18, 2013.
  205. ^ a b Urquhart, J. S.; Figura, C. C.; Moore, T. J. T.; Hoare, M. G.; et al. (January 2014). «The RMS Survey: Galactic distribution of massive star formation». Monthly Notices of the Royal Astronomical Society. 437 (2): 1791–1807. arXiv:1310.4758. Bibcode:2014MNRAS.437.1791U. doi:10.1093/mnras/stt2006. S2CID 14266458.
  206. ^ van Woerden, H.; et al. (1957). «Expansion d’une structure spirale dans le noyau du Système Galactique, et position de la radiosource Sagittarius A». Comptes Rendus de l’Académie des Sciences (in French). 244: 1691–1695. Bibcode:1957CRAS..244.1691V.
  207. ^ a b Dame, T. M.; Thaddeus, P. (2008). «A New Spiral Arm of the Galaxy: The Far 3-Kpc Arm». The Astrophysical Journal. 683 (2): L143–L146. arXiv:0807.1752. Bibcode:2008ApJ…683L.143D. doi:10.1086/591669. S2CID 7450090.
  208. ^ «Milky Way’s Inner Beauty Revealed». Center for Astrophysics | Harvard & Smithsonian. June 3, 2008. Archived from the original on July 5, 2013. Retrieved July 7, 2015.
  209. ^ Matson, John (September 14, 2011). «Star-Crossed: Milky Way’s Spiral Shape May Result from a Smaller Galaxy’s Impact». Scientific American. Archived from the original on December 3, 2013. Retrieved July 7, 2015.
  210. ^ Mel’Nik, A.; Rautiainen, A. (2005). «Kinematics of the outer pseudorings and the spiral structure of the Galaxy». Astronomy Letters. 35 (9): 609–624. arXiv:0902.3353. Bibcode:2009AstL…35..609M. CiteSeerX 10.1.1.247.4658. doi:10.1134/s1063773709090047. S2CID 15989486.
  211. ^ Mel’Nik, A. (2006). «Outer pseudoring in the galaxy». Astronomische Nachrichten. 326 (7): 589–605. arXiv:astro-ph/0510569. Bibcode:2005AN….326Q.599M. doi:10.1002/asna.200585006. S2CID 117118657.
  212. ^ Lopez-Corredoira, M.; et al. (July 2012). «Comments on the «Monoceros» affair». arXiv:1207.2749 [astro-ph.GA].
  213. ^ Byrd, Deborah (February 5, 2019). «The Milky Way is warped». EarthSky. Archived from the original on February 6, 2019. Retrieved February 6, 2019.
  214. ^ Harris, William E. (February 2003). «Catalog of Parameters for Milky Way Globular Clusters: The Database» (text). SEDS. Archived from the original on March 9, 2012. Retrieved May 10, 2007.
  215. ^ Dauphole, B.; et al. (September 1996). «The kinematics of globular clusters, apocentric distances and a halo metallicity gradient». Astronomy and Astrophysics. 313: 119–128. Bibcode:1996A&A…313..119D.
  216. ^ Gnedin, O. Y.; Lee, H. M.; Ostriker, J. P. (1999). «Effects of Tidal Shocks on the Evolution of Globular Clusters». The Astrophysical Journal. 522 (2): 935–949. arXiv:astro-ph/9806245. Bibcode:1999ApJ…522..935G. doi:10.1086/307659. S2CID 11143134.
  217. ^ Janes, K.A.; Phelps, R.L. (1980). «The galactic system of old star clusters: The development of the galactic disk». The Astronomical Journal. 108: 1773–1785. Bibcode:1994AJ….108.1773J. doi:10.1086/117192.
  218. ^ Ibata, R.; et al. (2005). «On the accretion origin of a vast extended stellar disk around the Andromeda Galaxy». The Astrophysical Journal. 634 (1): 287–313. arXiv:astro-ph/0504164. Bibcode:2005ApJ…634..287I. doi:10.1086/491727. S2CID 17803544.
  219. ^ «Outer Disk Ring?». SolStation. Archived from the original on June 2, 2007. Retrieved May 10, 2007.
  220. ^ T.M. Dame; P. Thaddeus (2011). «A Molecular Spiral Arm in the Far Outer Galaxy». The Astrophysical Journal. 734 (1): L24. arXiv:1105.2523. Bibcode:2011ApJ…734L..24D. doi:10.1088/2041-8205/734/1/l24. S2CID 118301649.
  221. ^ Jurić, M.; et al. (February 2008). «The Milky Way Tomography with SDSS. I. Stellar Number Density Distribution». The Astrophysical Journal. 673 (2): 864–914. arXiv:astro-ph/0510520. Bibcode:2008ApJ…673..864J. doi:10.1086/523619. S2CID 11935446.
  222. ^ Boen, Brooke. «NASA’s Chandra Shows Milky Way is Surrounded by Halo of Hot Gas». Brooke Boen. Archived from the original on October 23, 2012. Retrieved October 28, 2012.
  223. ^ Gupta, A.; Mathur, S.; Krongold, Y.; Nicastro, F.; Galeazzi, M. (2012). «A Huge Reservoir of Ionized Gas Around the Milky Way: Accounting for the Missing Mass?». The Astrophysical Journal. 756 (1): L8. arXiv:1205.5037. Bibcode:2012ApJ…756L…8G. doi:10.1088/2041-8205/756/1/L8. S2CID 118567708.
  224. ^ «Galactic Halo: Milky Way is Surrounded by Huge Halo of Hot Gas». Smithsonian Astrophysical Observatory. September 24, 2012. Archived from the original on October 29, 2012.
  225. ^ Communications, Discovery. «Our Galaxy Swims Inside a Giant Pool of Hot Gas». Discovery Communications. Archived from the original on October 29, 2012. Retrieved October 28, 2012.
  226. ^ a b J.D. Harrington; Janet Anderson; Peter Edmonds (September 24, 2012). «NASA’s Chandra Shows Milky Way is Surrounded by Halo of Hot Gas». NASA. Archived from the original on October 23, 2012.
  227. ^ Peter Schneider (2006). Extragalactic Astronomy and Cosmology. Springer. page 4, Fig. 1.4. ISBN 978-3-540-33174-2.
  228. ^ Jones, Mark H.; Lambourne, Robert J.; Adams, David John (2004). An Introduction to Galaxies and Cosmology. Cambridge University Press. p. 21; Fig. 1.13. ISBN 978-0-521-54623-2.
  229. ^ Camarillo, Tia; Dredger, Pauline; Ratra, Bharat (May 4, 2018). «Median Statistics Estimate of the Galactic Rotational Velocity». Astrophysics and Space Science. 363 (12): 268. arXiv:1805.01917. Bibcode:2018Ap&SS.363..268C. doi:10.1007/s10509-018-3486-8. S2CID 55697732.
  230. ^ Peter Schneider (2006). Extragalactic Astronomy and Cosmology. Springer. p. 413. ISBN 978-3-540-33174-2.
  231. ^ a b Staff (July 27, 2017). «Milky Way’s origins are not what they seem». Phys.org. Archived from the original on July 27, 2017. Retrieved July 27, 2017.
  232. ^ Borah, Debasish; Dutta, Manoranjan; Mahapatra, Satyabrata; Sahu, Narendra (2022). «Boosted self-interacting dark matter and XENON1T excess». Nuclear Physics B. 979: 115787. arXiv:2107.13176. Bibcode:2022NuPhB.97915787B. doi:10.1016/j.nuclphysb.2022.115787. S2CID 236469147.
  233. ^ Legassick, Daniel (2015). «The Age Distribution of Potential Intelligent Life in the Milky Way». arXiv:1509.02832 [astro-ph.GA].
  234. ^ Wethington, Nicholas (May 27, 2009). «Formation of the Milky Way». Universe Today. Archived from the original on August 17, 2014.
  235. ^ a b Buser, R. (2000). «The Formation and Early Evolution of the Milky Way Galaxy». Science. 287 (5450): 69–74. Bibcode:2000Sci…287…69B. doi:10.1126/science.287.5450.69. PMID 10615051.
  236. ^ Wakker, B. P.; Van Woerden, H. (1997). «High-Velocity Clouds». Annual Review of Astronomy and Astrophysics. 35: 217–266. Bibcode:1997ARA&A..35..217W. doi:10.1146/annurev.astro.35.1.217. S2CID 117861711.
  237. ^ Lockman, F. J.; et al. (2008). «The Smith Cloud: A High-Velocity Cloud Colliding with the Milky Way». The Astrophysical Journal. 679 (1): L21–L24. arXiv:0804.4155. Bibcode:2008ApJ…679L..21L. doi:10.1086/588838. S2CID 118393177.
  238. ^ Kruijssen, J M Diederik; Pfeffer, Joel L; Chevance, Mélanie; Bonaca, Ana; Trujillo-Gomez, Sebastian; Bastian, Nate; Reina-Campos, Marta; Crain, Robert A; Hughes, Meghan E (October 2020). «Kraken reveals itself – the merger history of the Milky Way reconstructed with the E-MOSAICS simulations». Monthly Notices of the Royal Astronomical Society. 498 (2): 2472–2491. arXiv:2003.01119. doi:10.1093/mnras/staa2452. Retrieved November 15, 2020.
  239. ^ Young, Monica (November 13, 2020). «Star Clusters reveal the «Kraken» in the Milky Way’s Past». Sky and Telescope. Retrieved November 15, 2020.
  240. ^ Yin, J.; Hou, J.L; Prantzos, N.; Boissier, S.; et al. (2009). «Milky Way versus Andromeda: a tale of two disks». Astronomy and Astrophysics. 505 (2): 497–508. arXiv:0906.4821. Bibcode:2009A&A…505..497Y. doi:10.1051/0004-6361/200912316. S2CID 14344453.
  241. ^ Hammer, F.; Puech, M.; Chemin, L.; Flores, H.; et al. (2007). «The Milky Way, an Exceptionally Quiet Galaxy: Implications for the Formation of Spiral Galaxies». The Astrophysical Journal. 662 (1): 322–334. arXiv:astro-ph/0702585. Bibcode:2007ApJ…662..322H. doi:10.1086/516727. S2CID 18002823.
  242. ^ Mutch, S.J.; Croton, D.J.; Poole, G.B. (2011). «The Mid-life Crisis of the Milky Way and M31». The Astrophysical Journal. 736 (2): 84. arXiv:1105.2564. Bibcode:2011ApJ…736…84M. doi:10.1088/0004-637X/736/2/84. S2CID 119280671.
  243. ^ Licquia, T.; Newman, J.A.; Poole, G.B. (2012). «What Is The Color Of The Milky Way?». American Astronomical Society. 219: 252.08. Bibcode:2012AAS…21925208L.
  244. ^ «A firestorm of star birth (artist’s illustration)». www.spacetelescope.org. ESA/Hubble. Archived from the original on April 13, 2015. Retrieved April 14, 2015.
  245. ^ Cayrel; et al. (2001). «Measurement of stellar age from uranium decay». Nature. 409 (6821): 691–692. arXiv:astro-ph/0104357. Bibcode:2001Natur.409..691C. doi:10.1038/35055507. PMID 11217852. S2CID 17251766.
  246. ^ Cowan, J. J.; Sneden, C.; Burles, S.; Ivans, I. I.; Beers, T. C.; Truran, J. W.; Lawler, J. E.; Primas, F.; Fuller, G. M.; et al. (2002). «The Chemical Composition and Age of the Metal‐poor Halo Star BD +17o3248». The Astrophysical Journal. 572 (2): 861–879. arXiv:astro-ph/0202429. Bibcode:2002ApJ…572..861C. doi:10.1086/340347. S2CID 119503888.
  247. ^ Krauss, L. M.; Chaboyer, B. (2003). «Age Estimates of Globular Clusters in the Milky Way: Constraints on Cosmology». Science. 299 (5603): 65–69. Bibcode:2003Sci…299…65K. doi:10.1126/science.1075631. PMID 12511641. S2CID 10814581.
  248. ^ Johns Hopkins University (November 5, 2018). «Johns Hopkins scientist finds elusive star with origins close to Big Bang». EurekAlert!. Archived from the original on November 6, 2018. Retrieved November 5, 2018.
  249. ^ Rosen, Jill (November 5, 2018). «Johns Hopkins scientist finds elusive star with origins close to Big Bang – The newly discovered star’s composition indicates that, in a cosmic family tree, it could be as little as one generation removed from the Big Bang». Johns Hopkins University. Archived from the original on November 6, 2018. Retrieved November 5, 2018.
  250. ^ Schlaufman, Kevin C.; Thompson, Ian B.; Casey, Andrew R. (November 5, 2018). «An Ultra Metal-poor Star Near the Hydrogen-burning Limit». The Astrophysical Journal. 867 (2): 98. arXiv:1811.00549. Bibcode:2018ApJ…867…98S. doi:10.3847/1538-4357/aadd97. S2CID 54511945.
  251. ^ a b Frebel, A.; et al. (2007). «Discovery of HE 1523-0901, a strongly r-process-enhanced metal-poor star with detected uranium». The Astrophysical Journal. 660 (2): L117. arXiv:astro-ph/0703414. Bibcode:2007ApJ…660L.117F. doi:10.1086/518122. S2CID 17533424.
  252. ^ «Hubble Finds Birth Certificate of Oldest Known Star in the Milky Way». NASA. March 7, 2013. Archived from the original on August 11, 2014.
  253. ^ Specktor, Brandon (March 23, 2019). «Astronomers Find Fossils of Early Universe Stuffed in Milky Way’s Bulge». Live Science. Archived from the original on March 23, 2019. Retrieved March 24, 2019.
  254. ^ del Peloso, E. F. (2005). «The age of the Galactic thin disk from Th/Eu nucleocosmochronology. III. Extended sample». Astronomy and Astrophysics. 440 (3): 1153–1159. arXiv:astro-ph/0506458. Bibcode:2005A&A…440.1153D. doi:10.1051/0004-6361:20053307. S2CID 16484977.
  255. ^ Skibba, Ramon (2016), «Milky Way retired early from star making» (New Scientist, March 5, 2016), p.9
  256. ^ Lynden-Bell, D. (March 1, 1976). «Dwarf Galaxies and Globular Clusters in High Velocity Hydrogen Streams». Monthly Notices of the Royal Astronomical Society. 174 (3): 695–710. Bibcode:1976MNRAS.174..695L. doi:10.1093/mnras/174.3.695. ISSN 0035-8711.
  257. ^ Kroupa, P.; Theis, C.; Boily, C. M. (2005). «The great disk of Milky-Way satellites and cosmological sub-structures». Astronomy and Astrophysics. 431 (2): 517–521. arXiv:astro-ph/0410421. Bibcode:2005A&A…431..517K. doi:10.1051/0004-6361:20041122.
  258. ^ Tully, R. Brent; Shaya, Edward J.; Karachentsev, Igor D.; Courtois, Hélène M.; Kocevski, Dale D.; Rizzi, Luca; Peel, Alan (March 2008). «Our Peculiar Motion Away from the Local Void». The Astrophysical Journal. 676 (1): 184–205. arXiv:0705.4139. Bibcode:2008ApJ…676..184T. doi:10.1086/527428. S2CID 14738309.
  259. ^ Hadhazy, Adam (November 3, 2016). «Why Nothing Really Matters». Discover Magazine. Retrieved April 24, 2022.
  260. ^ R. Brent Tully; Helene Courtois; Yehuda Hoffman; Daniel Pomarède (September 2, 2014). «The Laniakea supercluster of galaxies». Nature (published September 4, 2014). 513 (7516): 71–73. arXiv:1409.0880. Bibcode:2014Natur.513…71T. doi:10.1038/nature13674. PMID 25186900. S2CID 205240232.
  261. ^ De Vaucouleurs, Gerard; De Vaucouleurs, Antoinette; Corwin, Herold G.; Buta, Ronald J.; Paturel, Georges; Fouque, Pascal (1991). Third Reference Catalogue of Bright Galaxies. Bibcode:1991rc3..book…..D. doi:10.1007/978-1-4757-4363-0. ISBN 978-1-4757-4365-4.
  262. ^ Putman, M. E.; Staveley‐Smith, L.; Freeman, K. C.; Gibson, B. K.; Barnes, D. G. (2003). «The Magellanic Stream, High‐Velocity Clouds, and the Sculptor Group». The Astrophysical Journal. 586 (1): 170–194. arXiv:astro-ph/0209127. Bibcode:2003ApJ…586..170P. doi:10.1086/344477. S2CID 6911875.
  263. ^ Sergey E. Koposov; Vasily Belokurov; Gabriel Torrealba; N. Wyn Evans (March 10, 2015). «Beasts of the Southern Wild. Discovery of a large number of Ultra Faint satellites in the vicinity of the Magellanic Clouds». The Astrophysical Journal. 805 (2): 130. arXiv:1503.02079. Bibcode:2015ApJ…805..130K. doi:10.1088/0004-637X/805/2/130. S2CID 118267222.
  264. ^ Noyola, E.; Gebhardt, K.; Bergmann, M. (April 2008). «Gemini and Hubble Space Telescope Evidence for an Intermediate-Mass Black Hole in ω Centauri». The Astrophysical Journal. 676 (2): 1008–1015. arXiv:0801.2782. Bibcode:2008ApJ…676.1008N. doi:10.1086/529002. S2CID 208867075.
  265. ^ Lea Kivivali (June 11, 2014). «Nearby satellite galaxies challenge standard model of galaxy formation». Swinburne University of Technology. Archived from the original on March 16, 2015.
  266. ^ Pawlowski; et al. (June 10, 2014). «Co-orbiting satellite galaxy structures are still in conflict with the distribution of primordial dwarf galaxies». Monthly Notices of the Royal Astronomical Society. 442 (3): 2362–2380. arXiv:1406.1799. Bibcode:2014MNRAS.442.2362P. doi:10.1093/mnras/stu1005. S2CID 85454047.
  267. ^ «Milky Way Galaxy is warped and vibrating like a drum» (Press release). University of California, Berkeley. January 9, 2006. Archived from the original on July 16, 2014. Retrieved October 18, 2007.
  268. ^ Wong, Janet (April 14, 2000). «Astrophysicist maps out our own galaxy’s end». University of Toronto. Archived from the original on January 8, 2007. Retrieved January 11, 2007.
  269. ^ Junko Ueda; et al. (2014). «Cold molecular gas in merger remnants. I. Formation of molecular gas disks». The Astrophysical Journal Supplement Series. 214 (1): 1. arXiv:1407.6873. Bibcode:2014ApJS..214….1U. doi:10.1088/0067-0049/214/1/1. S2CID 716993.
  270. ^ Schiavi, Riccardo; Capuzzo-Dolcetta, Roberto; Arca-Sedda, Manuel; Spera, Mario (October 2020). «Future merger of the Milky Way with the Andromeda galaxy and the fate of their supermassive black holes». Astronomy & Astrophysics. 642: A30. arXiv:2102.10938. Bibcode:2020A&A…642A..30S. doi:10.1051/0004-6361/202038674. S2CID 224991193.
  271. ^ «The Velocity of Our Galaxy: the End of a 40-Year Mystery». CEA/The Knowledge Factory. January 31, 2017. Retrieved May 5, 2022.
  272. ^ «The Milky Way is being pushed through space by a void called the Dipole Repeller». Wired UK. Retrieved May 5, 2022.
  273. ^ Kocevski, D. D.; Ebeling, H. (2006). «On the origin of the Local Group’s peculiar velocity». The Astrophysical Journal. 645 (2): 1043–1053. arXiv:astro-ph/0510106. Bibcode:2006ApJ…645.1043K. doi:10.1086/503666. S2CID 2760455.
  274. ^ Peirani, S; Defreitaspacheco, J (2006). «Mass determination of groups of galaxies: Effects of the cosmological constant». New Astronomy. 11 (4): 325–330. arXiv:astro-ph/0508614. Bibcode:2006NewA…11..325P. doi:10.1016/j.newast.2005.08.008. S2CID 685068.
  275. ^ Lausten, Svend; Madsen, Claus; West, Richard M. (1987). Exploring the Southern Sky: a Pictorial Atlas from the European Southern Observatory (ESO). Berlin, Heidelberg: Springer. p. 119. ISBN 978-3-642-61588-7. OCLC 851764943.
  276. ^ Pasachoff, Jay M. (1994). Astronomy: From the Earth to the Universe. Harcourt School. p. 500. ISBN 978-0-03-001667-7.
  277. ^ Jones, Barrie William (2008). The Search for Life Continued: Planets Around Other Stars. Berlin: Springer. p. 89. ISBN 978-0-387-76559-4. OCLC 288474262.
  278. ^ Kruit, Pieter C. van der (2019). Jan Hendrik Oort: Master of the Galactic System. Cham, Switzerland: Springer. pp. 65, 717. ISBN 978-3-030-17801-7. OCLC 1110483488.
  279. ^ Hodge, Paul W.; et al. (October 13, 2020). «Milky Way Galaxy». Encyclopædia Britannica.

Further reading[edit]

  • Dambeck, Thorsten Dambeck (March 2008). «Gaia’s Mission to the Milky Way». Sky & Telescope: 36–39.
  • Chiappini, Cristina (November–December 2001). «The Formation and Evolution of the Milky Way» (PDF). American Scientist. 89 (6): 506–515. doi:10.1511/2001.40.745.

External links[edit]

Wikiquote has quotations related to Milky Way.

  • Milky Way – IRAS (infrared) survey – wikisky.org
  • Milky Way – H-Alpha survey – wikisky.org
  • Multiwavelength Milky Way – Images and VRML models (NASA)
  • Milky Way – Panorama (9 billion pixels).
  • Milky Way – SEDS Messier website
  • Milky Way – Infrared Images
  • Milky Way – Mosaic of galactic plane (March 19, 2021)
Источник

Млечный Путь

⇒ Правильное написание:

Млечный Путь

⇒ Гласные буквы в слове:

Млечный Путь

гласные выделены красным

гласными являются: е, ы, у

общее количество гласных: 3 (три)

• ударная гласная:

Мле́чный Пу́ть

ударная гласная выделена знаком ударения « ́»

ударение падает на буквы: е, у,

• безударные гласные:

Млечный Путь

безударные гласные выделены пунктирным подчеркиванием «  »

безударными гласными являются: ы

общее количество безударных гласных: 1 (одна)

⇒ Согласные буквы в слове:

Млечный Путь

согласные выделены зеленым

согласными являются: М, л, ч, н, й, П, т

общее количество согласных: 7 (семь)

• звонкие согласные:

Млечный Путь

звонкие согласные выделены одинарным подчеркиванием «  »

звонкими согласными являются: М, л, н, й

общее количество звонких согласных: 4 (четыре)

• глухие согласные:

Млечный Путь

глухие согласные выделены двойным подчеркиванием «  »

глухими согласными являются: ч, П, т

общее количество глухих согласных: 3 (три)

⇒ Беззвучные буквы в слове:

Млечный Путь

беззвучные выделены синим

беззвучными являются: ь

общее количество беззвучных: 1 (одна)

⇒ Формы слова:

Мле́чный Пу́ть

⇒ Количество букв и слогов:

гласных букв: 3 (три)

согласных букв: 7 (семь)

беззвучных букв: 1 (одна)

всего букв: 11 (одиннадцать)

всего слогов: 3 (три)

.

Источник

МЛЕЧНЫЙ ПУТЬ

Мл’ечный П’уть

Синонимы:

батыева дорога, галаксия, галактика, гусиная дорога, иерусалимская дорога, моисеева дорога, чумацкий шлях

МЛЕЮЩИЙ →← МЛЕЧНЫЙ

Синонимы слова «МЛЕЧНЫЙ ПУТЬ»:

ГАЛАКТИКА, БАТЫЕВА ДОРОГА, ГУСИНАЯ ДОРОГА, ИЕРУСАЛИМСКАЯ ДОРОГА, ГАЛАКСИЯ, МОИСЕЕВА ДОРОГА, ЧУМАЦКИЙ ШЛЯХ

Смотреть что такое МЛЕЧНЫЙ ПУТЬ в других словарях:

МЛЕЧНЫЙ ПУТЬ

(Батыева дорога) — скопление мельчайших звезд 8-й величины и ниже, представляющееся невооруженному глазу светлою полосою, растянутою через все небо (см… смотреть

МЛЕЧНЫЙ ПУТЬ

        неярко светящаяся диффузная белесая полоса, пересекающая звёздное небо почти по большому Кругу, северный полюс которого находится в созвездии В… смотреть

МЛЕЧНЫЙ ПУТЬ

млечный путь
сущ., кол-во синонимов: 7
• батыева дорога (3)
• галаксия (4)
• галактика (24)
• гусиная дорога (2)
• иерусалимская дорога (1)
• моисеева дорога (2)
• чумацкий шлях (1)
Словарь синонимов ASIS.В.Н. Тришин.2013.
.
Синонимы:
батыева дорога, галаксия, галактика, гусиная дорога, иерусалимская дорога, моисеева дорога, чумацкий шлях… смотреть

МЛЕЧНЫЙ ПУТЬ

МЛЕЧНЫЙ ПУТЬ, неярко светящаяся
диффузная белесая полоса, пересекающая звёздное небо почти по большому
кругу, северный полюс к-рого находится в созве… смотреть

МЛЕЧНЫЙ ПУТЬ

Млечный Путь (Батыева дорога) — скопление мельчайших звезд 8-й величины и ниже, представляющееся невооруженному глазу светлою полосою, растянутою через все небо (см. Карта звездного неба). Начиная от созвездия Единорог, М. Путь тянется, постепенно расширяясь, через созвездия Малого Пса, Близнецов, Возничего, Персея к Кассиопее; в Лебеде он разделяется на две полосы (бифуркация), которые продолжаются далее, почти параллельно одна другой, через созвездия Стрелы, Орда, Лиры, Офиуха, Стрельца, Скорпиона, Наугольника, Центавра и Южного Креста; здесь обе полосы снова сливаются в одну, но зато часто прерываются; наконец, в Корабле М. Путь составляет опять сплошную массу и направляется к Единорогу. В общем М. Путь тянется по большому кругу небесной сферы и пересекает эклиптику в двух противоположных точках, вблизи солнцестояний, под углом около 60°. Северный полюс М. пути имеет склонение +27° и прямое восхождение 12<sup>h</sup> 47<sup>m</sup>. Подобно тому, как в зодиакальной полосе неба, близ эклиптики, в плоскости М. Пути главным образом сосредоточены звезды видимого неба, по мере приближения к М. Пути число звезд постепенно увеличивается. Отсюда заключают, что эта полоса есть только кажущееся явление: все видимые звезды представляют огромную звездную кучу (см.), имеющую фигуру плоского и расщепленного в одном месте (бифуркация) диска, толщина которого незначительна по сравнению с его диаметром; звезды этой кучи распределены, вообще, довольно равномерно, но так как наше Солнце составляет одну из звезд М. Пути и находится приблизительно около ее центра, то жителям Земли она и представляется в виде сплошной полосы. <i> В. В. В</i>.<br><br><br>… смотреть

МЛЕЧНЫЙ ПУТЬ

МЛЕЧНЫЙ ПУТЬтуманное свечение на ночном небе от миллиардов звезд нашей Галактики. Полоса Млечного Пути опоясывает небосвод широким кольцом. Особенно хорошо Млечный Путь виден вдали от городских огней. В Северном полушарии его удобно наблюдать около полуночи в июле, в 10 часов вечера в августе или в 8 часов вечера в сентябре, когда Северный Крест созвездия Лебедь находится вблизи зенита. Следуя взглядом за мерцающей полосой Млечного Пути на север или северо-восток, мы минуем созвездие Кассиопеи (в форме буквы W) и движемся в сторону яркой звезды Капелла. За Капеллой можно увидеть, как менее широкая и яркая часть Млечного Пути проходит чуть восточнее Пояса Ориона и склоняется к горизонту невдалеке от Сириуса — ярчайшей звезды на небе. Наиболее яркая часть Млечного Пути видна на юге или юго-западе в то время, когда Северный Крест находится над головой. При этом видны две ветви Млечного Пути, разделенные темным промежутком. Облако в Щите, которое Э. Барнард называл «жемчужиной Млечного Пути», располагается на полпути к зениту, а ниже видны великолепные созвездия Стрелец и Скорпион.К сожалению, самые яркие части Млечного Пути недоступны для наблюдателей Северного полушария. Чтобы увидеть их, нужно отправиться к экватору, а еще лучше — расположиться между 20 и 40? ю.ш. и наблюдать небо ок. 10 ч вечера в конце апреля или начале мая. Высоко на небосводе расположен Южный Крест, а низко на северо-западе виден Сириус. Между ними проходит неяркий и узкий Млечный Путь, но он становится намного ярче и интереснее в 30? к западу от Южного Креста, в созвездии Киля. По мере того как на востоке поднимаются Стрелец и Скорпион, появляются самые яркие и великолепные части Млечного Пути. Наиболее замечательная его область видна поздним вечером в июне-июле, когда Облако Стрельца расположено вблизи зенита. На фоне однородного свечения, вызванного тысячами и тысячами не различимых для глаза далеких звезд, можно заметить темные облака и «прожилки» холодной космической пыли. Каждый, кто хочет понять строение нашей Галактики, должен найти время для наблюдения Млечного Пути — этого поистине замечательного и наиболее грандиозного из небесных явлений.Чтобы различить мириады звезд, составляющих Млечный Путь, достаточно бинокля или небольшого телескопа. Наибольшая концентрация звезд и максимальная ширина Млечного Пути наблюдаются в созвездиях Стрельца и Скорпиона; наименее населен звездами он на противоположной стороне неба — вблизи Пояса Ориона и Капеллы. Точные астрономические наблюдения подтверждают первое визуальное впечатление: полоса Млечного Пути отмечает центральную плоскость гигантской дискообразной звездной системы — нашей Галактики, которую часто называют «галактика Млечный Путь». Одной из ее звезд является наше Солнце, расположенное очень близко от центральной плоскости Галактики. Однако Солнце находится не в центре галактического диска, а на расстоянии двух третей от его центра к краю. Звезды, составляющие Млечный Путь, находятся от Земли на разных расстояниях: некоторые не далее 100 св. лет, а большинство удалено на 10 000 св. лет и даже дальше. Звездное облако в Стрельце и Скорпионе отмечает направление на центр Галактики, находящийся от Земли приблизительно на расстоянии 30 000 св. лет. Диаметр всей Галактики составляет по крайней мере 100 000 св. лет.Состав Млечного Пути. Галактика состоит в основном из звезд, более или менее подобных Солнцу. Одни из них в несколько раз массивнее Солнца и светятся в несколько тысяч раз ярче, другие — в несколько раз менее массивны и светятся в несколько тысяч раз слабее. Солнце, по многим параметрам, — средняя звезда. В зависимости от температуры поверхности звезды имеют разный цвет: бело-голубые звезды самые горячие (20 000-40 000 К), а красные — наиболее холодные (ок. 2500 К).Часть звезд образует группы, называемые звездными скоплениями. Некоторые из них видны невооруженным глазом, например Плеяды. Это типичное рассеянное скопление; обычно такие скопления содержат от 50 до 2000 звезд. Кроме рассеянных скоплений существуют значительно более крупные шаровые скопления, содержащие до нескольких миллионов звезд. Эти скопления существенно различаются по возрасту и звездному составу. Рассеянные скопления сравнительно молоды: их типичный возраст ок. 10 млн. лет, т.е. ок. 1/500 возраста Земли и Солнца. Они содержат много массивных ярких звезд. Шаровые скопления очень стары: с момента их формирования прошло 10-15 млрд. лет, т.е. они состоят из наиболее старых звезд Галактики, среди которых сохранились лишь маломассивные. Рассеянные скопления расположены вблизи галактической плоскости, где много межзвездного газа, из которого формируются звезды. Шаровые скопления заполняют галактическое гало, окружающее диск, и заметно концентрируются к центру Галактики. См. также ГАЛАКТИКИ; ЗВЕЗДЫ; СОЗВЕЗДИЕ.Масса Галактики не менее 2?1011 масс Солнца. В основном это звезды, но 5% ее массы приходится на межзвездное вещество — газ и пыль. Межзвездное вещество заполняет пространство между звездами в галактическом диске толщиной ок. 600 св. лет, причем внутри диска оно концентрируется к спиральным рукавам Галактики. Значительная часть межзвездного вещества объединена в массивные холодные облака, в недрах которых формируются звезды. См. также МЕЖЗВЕЗДНОЕ ВЕЩЕСТВО.Галактика Млечный Путь — одна из сотен миллионов подобных ей звездных систем, обнаруженных во Вселенной с помощью крупных телескопов. Ее часто называют «нашей звездной системой». Она относится к крупным галактикам, имеющим быстрое вращение и четкие спиральные рукава, в которых сконцентрированы молодые горячие звезды и разогретые их излучением облака газа, называемые «эмиссионными туманностями». С помощью оптических телескопов не удается изучить всю Галактику, поскольку свет не проникает сквозь плотные межзвездные облака газа и пыли, которых особенно много в направлении к центру Галактики. Однако для инфракрасного излучения и радиоизлучения пыль не помеха: с помощью соответствующих телескопов удается исследовать всю Галактику и даже пробиться к ее плотному ядру. Наблюдения показали, что звезды и газ в галактическом диске движутся со скоростью около 250 км/с вокруг центра Галактики. Наше Солнце вместе с планетами тоже движется с такой скоростью, совершая один оборот вокруг галактического центра примерно за 200 млн. лет…. смотреть

МЛЕЧНЫЙ ПУТЬ

        (греч. galaxias от gala — молоко). Происхождение назв. «М. п.» связано с греч. мифом о струе молока, брызнувшей на небо, когда Гера оторвала от… смотреть

МЛЕЧНЫЙ ПУТЬ

1) Орфографическая запись слова: млечный путь2) Ударение в слове: Мл`ечный П`уть3) Деление слова на слоги (перенос слова): млечный путь4) Фонетическая … смотреть

МЛЕЧНЫЙ ПУТЬ

Звездная галактика, членом которой является Солнце, движущаяся по орбите вокруг Галактического центра, располагается в направлении 0о Козерога. Звезд… смотреть

МЛЕЧНЫЙ ПУТЬ

галактика, к которой принадлежит наше Солнце (см. Галактика, Солнце). Галактика — это гигантская звездная система, состоящая приблизительно из 200 млрд. звезд. В ней также содержится значительное количество газа и пыли; галактика пронизана магнитными полями, заполнена частицами высоких энергий — космическими лучами. Звезды галактики образуют в пространстве сложную, но достаточно правильную фигуру, которая выглядит как плоский диск с шарообразным утолщением в центре (иногда его называют балдж, англ. выпуклость). От центральной области к периферии диска отходят спиральные рукава, в которых преимущественно концентрируются наиболее яркие звезды. В соответствии с этой особенностью структуры, нашу галактику относят к классу спиральных галактик. … смотреть

МЛЕЧНЫЙ ПУТЬ

Скопление огромного количества слабых звёзд и туманностей, представляющееся невооружённому глазу светлой полосой неправильной формы, растянутой по небесному своду. <em>Как розово-палевое зарево, сиял блеск Млечного Пути</em> (Гончаров. Фрегат «Паллада»). <em>Млечный Путь серебристой тканью разостлался по небу от края до края</em> (М. Горький. Трое). <em>Над садом, мерцая в прудах, высыпали бесчисленные звёзды, облачным светом белел Млечный Путь</em> (А. Н. Толстой. Граф Калиостро).<br><b>Синонимы</b>: <div class=»tags_list»>
батыева дорога, галаксия, галактика, гусиная дорога, иерусалимская дорога, моисеева дорога, чумацкий шлях
</div><br><br>… смотреть

МЛЕЧНЫЙ ПУТЬ

— 1) Галактика. 2 )Светлая полоса на ночном небе — проекция на небесную сферу удалённых (от Солнца) звёзд Галактики, близких к её плоскости. Повыш… смотреть

МЛЕЧНЫЙ ПУТЬ

▲ галактика↑ (быть) в, который, располагаться, СОЛНЕЧНАЯ СИСТЕМАсистема Млечного пути — галактика, в которой расположена Солнечная система. Галактика.г… смотреть

МЛЕЧНЫЙ ПУТЬ

Млечный путь — широкая полоса на небѣ, состоящая изъ безчисленныхъ звѣздъ.
Ср. Все небо усыпано весело мигающими звѣздами, и млечный путь вырисовывает… смотреть

МЛЕЧНЫЙ ПУТЬ

широкая полоса на небе, состоящая из бесчисленных звезд
Ср. Все небо усыпано весело мигающими звездами, и млечный путь вырисовывается так ясно, как буд… смотреть

МЛЕЧНЫЙ ПУТЬ

МЛЕЧНЫЙ ПУТЬ, слабосветящаяся полоса, видимая на небе в ясные темные ночи, проходящая по линии галактического экватора. Она образуется в результате све… смотреть

МЛЕЧНЫЙ ПУТЬ

1) Пересекающая звездное небо неярко светящаяся полоса. Представляет собой огромное количество визуально неразличимых звезд, концентрирующихся к основной плоскости Галактики. Близ этой плоскости расположено Солнце, так что большинство звезд Галактики проецируется на небесную сферу в пределах узкой полосы — Млечного Пути.
2) Собственно название Галактики.
Астрономический словарь.EdwART.2010.
Синонимы:
батыева дорога, галаксия, галактика, гусиная дорога, иерусалимская дорога, моисеева дорога, чумацкий шлях… смотреть

МЛЕЧНЫЙ ПУТЬ

1) пересекающая звёздное небо неярко светящаяся полоса. Представляет собой огромное кол-во визуально неразличимых звёзд, концентрирующихся к осн. плоск… смотреть

МЛЕЧНЫЙ ПУТЬ

1) собственно название нашей Галактики;
2) неярко светящаяся полоса звездного неба, в которой сосредоточены миллиарды визуально неразличимых звезд, концентрирующиеся к основной плоскости Галактики.
Начала современного естествознания. Тезаурус. — Ростов-на-Дону.В.Н. Савченко, В.П. Смагин.2006.
Синонимы:
батыева дорога, галаксия, галактика, гусиная дорога, иерусалимская дорога, моисеева дорога, чумацкий шлях… смотреть

МЛЕЧНЫЙ ПУТЬ

,
1) пересекающая звездное небо неярко светящаяся полоса. Представляет собой огромное количество визуально неразличимых звезд, концентрирующихся к осн… смотреть

МЛЕЧНЫЙ ПУТЬ

МЛЕЧНЫЙ ПУТЬ, 1) пересекающая звездное небо неярко светящаяся полоса. Представляет собой огромное количество визуально неразличимых звезд, концентрирующихся к основной плоскости Галактики. Близ этой плоскости расположено Солнце, так что большинство звезд Галактики проецируется на небесную сферу в пределах узкой полосы — Млечного Пути.2) Собственно название Галактики.<br><br><br>… смотреть

МЛЕЧНЫЙ ПУТЬ

МЛЕЧНЫЙ ПУТЬ, 1) пересекающая звездное небо неярко светящаяся полоса. Представляет собой огромное количество визуально неразличимых звезд, концентрирующихся к основной плоскости Галактики. Близ этой плоскости расположено Солнце, так что большинство звезд Галактики проецируется на небесную сферу в пределах узкой полосы — млечного пути. 2) Собственно название Галактики. <br>… смотреть

МЛЕЧНЫЙ ПУТЬ

МЛЕЧНЫЙ ПУТЬ -1) пересекающая звездное небо неярко светящаяся полоса. Представляет собой огромное количество визуально неразличимых звезд, концентрирующихся к основной плоскости Галактики. Близ этой плоскости расположено Солнце, так что большинство звезд Галактики проецируется на небесную сферу в пределах узкой полосы — Млечного Пути.2) Собственно название Галактики.<br>… смотреть

МЛЕЧНЫЙ ПУТЬ

МЛЕЧНЫЙ ПУТЬ ,1) пересекающая звездное небо неярко светящаяся полоса. Представляет собой огромное количество визуально неразличимых звезд, концентрирующихся к основной плоскости Галактики. Близ этой плоскости расположено Солнце, так что большинство звезд Галактики проецируется на небесную сферу в пределах узкой полосы — Млечного Пути.2) Собственно название Галактики…. смотреть

МЛЕЧНЫЙ ПУТЬ

МЛЕЧНЫЙ ПУТЬ,1) пересекающая звездное небо неярко светящаяся полоса. Представляет собой огромное количество визуально неразличимых звезд, концентрирующихся к основной плоскости Галактики. Близ этой плоскости расположено Солнце, так что большинство звезд Галактики проецируется на небесную сферу в пределах узкой полосы — Млечного Пути.2) Собственно название Галактики…. смотреть

МЛЕЧНЫЙ ПУТЬ

— пересекающая звездное небо неярко светящаяся полоса.Представляет собой огромное количество визуально неразличимых звезд,концентрирующихся к основной плоскости Галактики. Близ этой плоскостирасположено Солнце, так что большинство звезд Галактики проецируется нанебесную сферу в пределах узкой полосы — Млечного Пути.2) Собственноназвание Галактики…. смотреть

МЛЕЧНЫЙ ПУТЬ

Млечный путьשבִיל הֶחָלָב ז’* * *שביל החלבСинонимы:
батыева дорога, галаксия, галактика, гусиная дорога, иерусалимская дорога, моисеева дорога, чумацк… смотреть

МЛЕЧНЫЙ ПУТЬ

астр. 银河; 天河Синонимы: батыева дорога, галаксия, галактика, гусиная дорога, иерусалимская дорога, моисеева дорога, чумацкий шлях

МЛЕЧНЫЙ ПУТЬ

астр.Milchstraße fСинонимы: батыева дорога, галаксия, галактика, гусиная дорога, иерусалимская дорога, моисеева дорога, чумацкий шлях

МЛЕЧНЫЙ ПУТЬ

астр Via LácteaСинонимы: батыева дорога, галаксия, галактика, гусиная дорога, иерусалимская дорога, моисеева дорога, чумацкий шлях

МЛЕЧНЫЙ ПУТЬ

SamanyoluСинонимы: батыева дорога, галаксия, галактика, гусиная дорога, иерусалимская дорога, моисеева дорога, чумацкий шлях

МЛЕЧНЫЙ ПУТЬ

(астр.)Синонимы: батыева дорога, галаксия, галактика, гусиная дорога, иерусалимская дорога, моисеева дорога, чумацкий шлях

МЛЕЧНЫЙ ПУТЬ

1) galaxy2) via lacteaСинонимы: батыева дорога, галаксия, галактика, гусиная дорога, иерусалимская дорога, моисеева дорога, чумацкий шлях

МЛЕЧНЫЙ ПУТЬ

Ударение в слове: Мл`ечный П`утьУдарение падает на буквы: е,уБезударные гласные в слове: Мл`ечный П`уть

МЛЕЧНЫЙ ПУТЬ

Начальная форма — Млечный путь, винительный падеж, слово обычно не имеет множественного числа, единственное число, мужской род, неодушевленное, организация… смотреть

Источник

§ 178. В
названиях небесных тел, созвездий и галактик с прописной буквы пишутся все
слова, кроме родовых наименований (звезда, комета, созвездие,
планета, астероид и т. п.) и буквенных обозначений светил (альфа, бета, гамма и т. п.), напр.: Венера,
Сатурн, альфа Малой Медведицы, звезда Эрцгерцога Карла, Капелла Возничего,
Млечный Путь, созвездие Большого Пса, туманность Андромеды, Южный Крест,
галактика Большое Магелланово Облако; Дева, Водолей, Стрелец (созвездия
и знаки зодиака); Солнце, Земля, Луна. Так же пишутся
названия местностей на космических телах, напр.: Болото Гнили,
Залив Радуги, Море Дождей, Океан Бурь (на Луне), где слова болото, залив и т. д. употребляются не в своем обычном
значении.

Примечание. Слова солнце, земля, луна не как
астрономические названия пишутся со строчной буквы: закат солнца, обработка земли, свет луны
(ср.: полёт на Луну, протуберанцы
на Солнце, происхождение Земли).

Источник

Понравилась статья? Поделить с друзьями:
  • Как написать правильно кроме воскресенья или воскресения
  • Как написать правильно красотулечка или красатулечка
  • Как написать пояснительную записку директору образец
  • Как написать пояснительная записка образец
  • Как написать пояснения к иску