Английская Википедия:Andromeda (constellation)

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Шаблон:Short description Шаблон:Other uses Шаблон:Use shortened footnotes Шаблон:Infobox constellation Andromeda is one of the 48 constellations listed by the 2nd-century Greco-Roman astronomer Ptolemy, and one of the 88 modern constellations. Located in the northern celestial hemisphere, it is named for Andromeda, daughter of Cassiopeia, in the Greek myth, who was chained to a rock to be eaten by the sea monster Cetus. Andromeda is most prominent during autumn evenings in the Northern Hemisphere, along with several other constellations named for characters in the Perseus myth. Because of its northern declination, Andromeda is visible only north of 40° south latitude; for observers farther south, it lies below the horizon. It is one of the largest constellations, with an area of 722 square degrees. This is over 1,400 times the size of the full moon, 55% of the size of the largest constellation, Hydra, and over 10 times the size of the smallest constellation, Crux.

Its brightest star, Alpha Andromedae, is a binary star that has also been counted as a part of Pegasus, while Gamma Andromedae is a colorful binary and a popular target for amateur astronomers. Only marginally dimmer than Alpha, Beta Andromedae is a red giant, its color visible to the naked eye. The constellation's most obvious deep-sky object is the naked-eye Andromeda Galaxy (M31, also called the Great Galaxy of Andromeda), the closest spiral galaxy to the Milky Way and one of the brightest Messier objects. Several fainter galaxies, including M31's companions M110 and M32, as well as the more distant NGC 891, lie within Andromeda. The Blue Snowball Nebula, a planetary nebula, is visible in a telescope as a blue circular object.

In Chinese astronomy, the stars that make up Andromeda were members of four different constellations that had astrological and mythological significance; a constellation related to Andromeda also exists in Hindu mythology. Andromeda is the location of the radiant for the Andromedids, a weak meteor shower that occurs in November.

History and mythology

Файл:Andromeda Hevelius.jpg
Johannes Hevelius's depiction of Andromeda, from the 1690 edition of his Uranographia. As was conventional for celestial atlases of the time, the constellation is a mirror image of modern maps as it was drawn from a perspective outside the celestial sphere.
Файл:Sidney Hall - Urania's Mirror - Gloria Frederici, Andromeda, and Triangula.jpg
Andromeda as depicted in Urania's Mirror, a set of constellation cards published in London c. 1825, showing the constellation from the inside of the celestial sphere
Файл:F19.v. Andromeda NLW MS 735C.png
Andromeda depicted in an early scientific manuscript, c.1000

The uranography of Andromeda has its roots most firmly in the Greek tradition, though a female figure in Andromeda's location had appeared earlier in Babylonian astronomy. The stars that make up Pisces and the middle portion of modern Andromeda formed a constellation representing a fertility goddess, sometimes named as Anunitum or the Lady of the Heavens.Шаблон:Sfn

Andromeda is known as "the Chained Lady" or "the Chained Woman" in English. It was known as Mulier Catenata ("chained woman") in Latin and al-Mar'at al Musalsalah in Arabic.Шаблон:Sfn It has also been called Persea ("Perseus's wife") or Cepheis ("Cepheus's daughter"),Шаблон:SfnШаблон:Sfn all names that refer to Andromeda's role in the Greco-Roman myth of Perseus, in which Cassiopeia, the queen of Ethiopia, bragged that her daughter was more beautiful than the Nereids, sea nymphs blessed with incredible beauty.Шаблон:Sfn Offended at her remark, the nymphs petitioned Poseidon to punish Cassiopeia for her insolence, which he did by commanding the sea monster Cetus to attack Ethiopia.Шаблон:Sfn Andromeda's panicked father, Cepheus, was told by the Oracle of Ammon that the only way to save his kingdom was to sacrifice his daughter to Cetus.Шаблон:SfnШаблон:Sfn She was chained to a rock by the sea but was saved by the hero Perseus, who in one version of the story used the head of Medusa to turn the monster into stone;Шаблон:Sfn in another version, by the Roman poet Ovid in his Metamorphoses, Perseus slew the monster with his diamond sword.Шаблон:Sfn Perseus and Andromeda then married; the myth recounts that the couple had nine children together – seven sons and two daughters – and founded Mycenae and its Persideae dynasty. After Andromeda's death Athena placed her in the sky as a constellation, to honour her. Three of the neighbouring constellations (Perseus, Cassiopeia and Cepheus) represent characters in the Perseus myth, while Cetus retreats to beyond Pisces.Шаблон:Sfn It is connected with the constellation Pegasus.

Andromeda was one of the original 48 constellations formulated by Ptolemy in his 2nd-century Almagest, in which it was defined as a specific pattern of stars. She is typically depicted with α Andromedae as her head, ο and λ Andromedae as her chains, and δ, π, μ, β, and γ her body and legs. However, there is no universal depiction of Andromeda and the stars used to represent her body, head, and chains.Шаблон:Sfn Arab astronomers were aware of Ptolemy's constellations, but they included a second constellation representing a fish overlapping Andromeda's body; the nose of this fish was marked by a hazy patch that ‍we ‍now ‍know ‍as ‍the ‍Andromeda Galaxy, ‍M31.[1] Several stars from Andromeda and most of the stars in Lacerta were combined in 1787 by German astronomer Johann Bode to form Honores Friderici (also called Friedrichs Ehre). It was designed to honour King Frederick II of Prussia, but quickly fell into disuse.Шаблон:Sfn Since the time of Ptolemy, Andromeda has remained a constellation and is officially recognized by the International Astronomical Union. Like all those that date back to a pattern known to Ptolemy, it is attributed to a wider zone and thus many surrounding stars.Шаблон:SfnШаблон:Sfn In 1922, the IAU defined its recommended three-letter abbreviation, "And".Шаблон:Sfn The official boundaries of Andromeda were defined in 1930 by Belgian astronomer Eugène Delporte as a polygon of 36 segments. Its right ascension is between 22h 57.5m and 2h 39.3m and its declination is between 53.19° and 21.68° in the equatorial coordinate system.Шаблон:Sfn

In non-Western astronomy

Файл:AndromedaCC.jpg
Photo of the constellation Andromeda, as it appears to the naked eye. Lines have been added for clarity.

In traditional Chinese astronomy, nine stars from Andromeda (including Beta Andromedae, Mu Andromedae, and Nu Andromedae), along with seven stars from Pisces, formed an elliptical constellation called "Legs" (奎宿). This constellation either represented the foot of a walking person or a wild boar.Шаблон:Sfn Gamma Andromedae and its neighbours were called "Teen Ta Tseang Keun" (天大将军, heaven's great general), representing honour in astrology and a great general in mythology.Шаблон:SfnШаблон:Sfn Alpha Andromedae and Gamma Pegasi together made "Wall" (壁宿), representing the eastern wall of the imperial palace and/or the emperor's personal library. For the Chinese, the northern swath of Andromeda formed a stable for changing horses (Шаблон:Transl, 天厩, stable on sky) and the far western part, along with most of Lacerta, became Tengshe, a flying snake.Шаблон:Sfn

An Arab constellation called "al-Hut" (the fish) was composed of several stars in Andromeda, M31, and several stars in Pisces. ν And, μ And, β And, η And, ζ And, ε And, δ And, π And, and 32 And were all included from Andromeda; ν Psc, φ Psc, χ Psc, and ψ Psc were included from Pisces.Шаблон:Sfn

As per Hindu astronomy, Andromeda is known as Devyani Constellation while Cassiopeia is Sharmishta Constellation. Devyani and Sharmishta are wives of King Yayati (Perseus Constellation) who is the earliest patriarch of the Kuru and Yadu Clans that are mentioned frequently in epic Mahabharat. There is an interesting story of these three characters mentioned in Mahabharat. Devyani is the daughter of Guru Shukracharya while Shar.Шаблон:CN

Hindu legends surrounding Andromeda are similar to the Greek myths. Ancient Sanskrit texts depict Antarmada chained to a rock, as in the Greek myth. Scholars believe that the Hindu and Greek astrological myths were closely linked; one piece of evidence cited is the similarity between the names "Antarmada" and "Andromeda".Шаблон:Sfn

Andromeda is also associated with the Mesopotamian creation story of Tiamat, the goddess of Chaos. She bore many demons for her husband, Apsu, but eventually decided to destroy them in a war that ended when Marduk killed her. He used her body to create the constellations as markers of time for humans.Шаблон:SfnШаблон:Sfn

In the Marshall Islands, Andromeda, Cassiopeia, Triangulum, and Aries are incorporated into a constellation representing a porpoise. Andromeda's bright stars are mostly in the body of the porpoise; Cassiopeia represents its tail and Aries its head.Шаблон:Sfn In the Tuamotu islands, Alpha Andromedae was called Takurua-e-te-tuki-hanga-ruki, meaning "Star of the wearisome toil",Шаблон:Sfn and Beta Andromedae was called Piringa-o-Tautu.Шаблон:Sfn

Features

Stars

Шаблон:Further

Файл:Andromeda annotated.png
Andromeda as it appears in the night sky, with the superimposed figure.
A Hertzsprung-Russel diagram for stars above 4th magnitude in the Andromeda constellation (axes not labelled).
A Hertzsprung–Russell diagram for stars brighter than 4th magnitude in the constellation Andromeda (axes not labelled).

Of the stars brighter than 4th magnitude (and those with measured luminosity), Andromeda has a relatively even distribution of evolved and main-sequence stars.

Deep-sky objects

Файл:M31bobo.jpg
M31, the Great Galaxy of Andromeda.

Andromeda's borders contain many visible distant galaxies.Шаблон:Sfn The most famous deep-sky object in Andromeda is the spiral galaxy cataloged as Messier 31 (M31) or NGC 224 but known colloquially as the Andromeda Galaxy for the constellation.Шаблон:Sfn M31 is one of the most distant objects visible to the naked eye, 2.2 million light-years from Earth (estimates range up to 2.5 million light-years).Шаблон:Sfn It is seen under a dark, transparent sky as a hazy patch in the north of the constellation.Шаблон:Sfn M31 is the largest neighboring galaxy to the Milky Way and the largest member of the Local Group of galaxies.Шаблон:SfnШаблон:Sfn In absolute terms, M31 is approximately 200,000 light-years in diameter, twice the size of the Milky Way.Шаблон:Sfn It is an enormous – 192.4 by 62.2 arcminutes in apparent sizeШаблон:Sfn – barred spiral galaxy similar in form to the Milky Way and at an approximate magnitude of 3.5, is one of the brightest deep-sky objects in the northern sky.Шаблон:Sfn Despite being visible to the naked eye, the "little cloud" near Andromeda's figure was not recorded until AD 964, when the Arab astronomer al-Sufi wrote his Book of Fixed Stars.Шаблон:SfnШаблон:Sfn M31 was first observed telescopically shortly after its invention, by Simon Marius in 1612.Шаблон:Sfn

The future of the Andromeda and Milky Way galaxies may be interlinked: in about five billion years, the two could potentially begin an Andromeda–Milky Way collision that would spark extensive new star formation.Шаблон:Sfn

Файл:Andromeda Galaxy M31 - Heic1502a 10k.jpg
Sharp view of the Andromeda Galaxy[4]

American astronomer Edwin Hubble included M31 (then known as the Andromeda Nebula) in his groundbreaking 1923 research on galaxies.Шаблон:Sfn Using the 100-inch Hooker Telescope at Mount Wilson Observatory in California, he observed Cepheid variable stars in M31 during a search for novae, allowing him to determine their distance by using the stars as standard candles.Шаблон:Sfn The distance he found was far greater than the size of the Milky Way, which led him to the conclusion that many similar objects were "island universes" on their own.Шаблон:SfnШаблон:SfnШаблон:Sfn Hubble originally estimated that the Andromeda Galaxy was 900,000 light-years away, but Ernst Öpik's estimate in 1925 put the distance closer to 1.5 million light-years.Шаблон:Sfn

The Andromeda Galaxy's two main companions, M32 and M110 (also known as NGC 221 and NGC 205, respectively) are faint elliptical galaxies that lie near it.Шаблон:SfnШаблон:Sfn M32, visible with a far smaller size of 8.7 by 6.4 arcminutes,Шаблон:Sfn compared to M110, appears superimposed on the larger galaxy in a telescopic view as a hazy smudge, M110 also appears slightly larger and distinct from the larger galaxy;Шаблон:Sfn M32 is 0.5° south of the core, M110 is 1° northwest of the core.Шаблон:Sfn M32 was discovered in 1749 by French astronomer Guillaume Le Gentil and has since been found to lie closer to Earth than the Andromeda Galaxy itself.Шаблон:Sfn It is viewable in binoculars from a dark site owing to its high surface brightness of 10.1 and overall magnitude of 9.0.Шаблон:Sfn M110 is classified as either a dwarf spheroidal galaxy or simply a generic elliptical galaxy. It is far fainter than M31 and M32, but larger than M32 with a surface brightness of 13.2, magnitude of 8.9, and size of 21.9 by 10.9 arcminutes.Шаблон:Sfn

The Andromeda Galaxy has a total of 15 satellite galaxies, including M32 and M110. Nine of these lie in a plane, which has caused astronomers to infer that they have a common origin. These satellite galaxies, like the satellites of the Milky Way, tend to be older, gas-poor dwarf elliptical and dwarf spheroidal galaxies.Шаблон:Sfn

Файл:NGC 7662 Hubble WikiSky.jpg
The Blue Snowball Nebula as seen through the Hubble Space Telescope.

Along with the Andromeda Galaxy and its companions, the constellation also features NGC 891 (Caldwell 23), a smaller galaxy just east of Almach. It is a barred spiral galaxy seen edge-on, with a dark dust lane visible down the middle. NGC 891 is incredibly faint and small despite its magnitude of 9.9,Шаблон:Sfn as its surface brightness of 14.6 indicates;Шаблон:Sfn it is 13.5 by 2.8 arcminutes in size.Шаблон:Sfn NGC 891 was discovered by the brother-and-sister team of William and Caroline Herschel in August 1783.Шаблон:Sfn This galaxy is at an approximate distance of 30 million light-years from Earth, calculated from its redshift of 0.002.Шаблон:Sfn

Andromeda's most celebrated open cluster is NGC 752 (Caldwell 28) at an overall magnitude of 5.7.Шаблон:Sfn It is a loosely scattered cluster in the Milky Way that measures 49 arcminutes across and features approximately twelve bright stars, although more than 60 stars of approximately 9th magnitude become visible at low magnifications in a telescope.Шаблон:SfnШаблон:Sfn It is considered to be one of the more inconspicuous open clusters.Шаблон:Sfn The other open cluster in Andromeda is NGC 7686, which has a similar magnitude of 5.6 and is also a part of the Milky Way. It contains approximately 20 stars in a diameter of 15 arcminutes, making it a tighter cluster than NGC 752.Шаблон:Sfn

There is one prominent planetary nebula in Andromeda: NGC 7662 (Caldwell 22).Шаблон:Sfn Lying approximately 3 degrees southwest of Iota Andromedae at a distance of about 4,000 light-years from Earth, the "Blue Snowball Nebula"Шаблон:Sfn is a popular target for amateur astronomers.Шаблон:Sfn It earned its popular name because it appears as a faint, round, blue-green object in a telescope, with an overall magnitude of 9.2.Шаблон:SfnШаблон:Sfn Upon further magnification, it is visible as a slightly elliptical annular disk that gets darker towards the center, with a magnitude 13.2 central star.Шаблон:SfnШаблон:Sfn The nebula has an overall magnitude of 9.2 and is 20 by 130 arcseconds in size.Шаблон:Sfn

Meteor showers

Each November, the Andromedids meteor shower appears to radiate from Andromeda.Шаблон:Sfn The shower peaks in mid-to-late November every year, but has a low peak rate of fewer than 2 meteors per hour.Шаблон:Sfn Astronomers have often associated the Andromedids with Biela's Comet, which was destroyed in the 19th century, but that connection is disputed.Шаблон:Sfn Andromedid meteors are known for being very slow and the shower itself is considered to be diffuse, as meteors can be seen coming from nearby constellations as well as from Andromeda itself.Шаблон:Sfn Andromedid meteors sometimes appear as red fireballs.Шаблон:SfnШаблон:Sfn The Andromedids were associated with the most spectacular meteor showers of the 19th century; the storms of 1872 and 1885 were estimated to have a peak rate of 2 meteors per second (a zenithal hourly rate of 10,000), prompting a Chinese astronomer to compare the meteors to falling rain.Шаблон:SfnШаблон:Sfn The Andromedids had another outburst on December 3–5, 2011, the most active shower since 1885, with a maximum zenithal hourly rate of 50 meteors per hour. The 2011 outburst was linked to ejecta from Comet Biela, which passed close to the Sun in 1649. None of the meteoroids observed were associated with material from the comet's 1846 disintegration. The observers of the 2011 outburst predicted outbursts in 2018, 2023, and 2036.Шаблон:Sfn

See also

References

Citations Шаблон:Reflist

Bibliography Шаблон:Refbegin

Шаблон:Refend

Online sources Шаблон:Refbegin

SIMBAD

Шаблон:Refend

External links

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  1. ↑ Шаблон:Cite web
  2. ↑ 2,0 2,1 2,2 Шаблон:Cite web
  3. ↑ Шаблон:Cite journal
  4. ↑ Шаблон:Cite web
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