Constellation | |
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Abbreviation | And [1] |
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Genitive | Andromedae |
Pronunciation |
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Symbolism | Andromeda, the Chained Woman [2] |
Right ascension | 23h 25m 48.6945s–02h 39m 32.5149s [3] |
Declination | 53.1870041°–21.6766376° [3] |
Area | 722 [4] sq. deg. (19th) |
Main stars | 16 |
Bayer/Flamsteed stars | 65 |
Stars with planets | 12 |
Stars brighter than 3.00m | 3 |
Stars within 10.00 pc (32.62 ly) | 3 |
Brightest star | Alpheratz (α And) (2.07 m ) |
Messier objects | 3 [5] |
Meteor showers | Andromedids (Bielids) |
Bordering constellations | |
Visible at latitudes between +90° and −40°. Best visible at 21:00 (9 p.m.) during the month of November. |
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.
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. [7]
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. [2] It has also been called Persea ("Perseus's wife") or Cepheis ("Cepheus's daughter"), [2] [8] all names that refer to Andromeda's role in the Greco-Roman myth of Perseus, in which Cassiopeia, the queen of Aethiopia, bragged that her daughter was more beautiful than the Nereids, sea nymphs blessed with incredible beauty. [9] 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 Aethiopia. [9] 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. [10] [11] 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; [12] in another version, by the Roman poet Ovid in his Metamorphoses, Perseus slew the monster with his diamond sword. [11] 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. [10] 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. [13] 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. [14] 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. [15] 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. [16] [17] In 1922, the IAU defined its recommended three-letter abbreviation, "And". [18] 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. [3]
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. [11] 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. [8] [11] 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 (tianjiu, 天厩, stable on sky) and the far western part, along with most of Lacerta, became Tengshe, a flying snake. [11]
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 ψ1 Psc were included from Pisces. [19] [20]
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.[ citation needed ]
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". [8]
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. [8] [13]
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. [13] In the Tuamotu islands, Alpha Andromedae was called Takurua-e-te-tuki-hanga-ruki, meaning "Star of the wearisome toil", [21] and Beta Andromedae was called Piringa-o-Tautu. [22]
Of the stars brighter than 4th magnitude (and those with measured luminosity), Andromeda has a relatively even distribution of evolved and main-sequence stars.
Andromeda's borders contain many visible distant galaxies. [10] 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. [53] 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). [54] It is seen under a dark, transparent sky as a hazy patch in the north of the constellation. [54] M31 is the largest neighboring galaxy to the Milky Way and the largest member of the Local Group of galaxies. [53] [54] In absolute terms, M31 is approximately 200,000 light-years in diameter, twice the size of the Milky Way. [54] It is an enormous – 192.4 by 62.2 arcminutes in apparent size [10] – 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. [55] 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 . [11] [56] M31 was first observed telescopically shortly after its invention, by Simon Marius in 1612. [57]
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. [54]
American astronomer Edwin Hubble included M31 (then known as the Andromeda Nebula) in his groundbreaking 1923 research on galaxies. [56] 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. [59] 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. [60] [61] [62] 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. [59]
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. [5] [53] M32, visible with a far smaller size of 8.7 by 6.4 arcminutes, [10] 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; [53] M32 is 0.5° south of the core, M110 is 1° northwest of the core. [28] 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. [63] It is viewable in binoculars from a dark site owing to its high surface brightness of 10.1 and overall magnitude of 9.0. [10] 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. [10]
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. [64]
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, [23] as its surface brightness of 14.6 indicates; [10] it is 13.5 by 2.8 arcminutes in size. [23] NGC 891 was discovered by the brother-and-sister team of William and Caroline Herschel in August 1783. [54] This galaxy is at an approximate distance of 30 million light-years from Earth, calculated from its redshift of 0.002. [54]
Andromeda's most celebrated open cluster is NGC 752 (Caldwell 28) at an overall magnitude of 5.7. [23] 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. [10] [28] It is considered to be one of the more inconspicuous open clusters. [9] 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. [23]
There is one prominent planetary nebula in Andromeda: NGC 7662 (Caldwell 22). [23] Lying approximately 3 degrees southwest of Iota Andromedae at a distance of about 4,000 light-years from Earth, the "Blue Snowball Nebula" [10] is a popular target for amateur astronomers. [65] 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. [10] [65] 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. [10] [28] The nebula has an overall magnitude of 9.2 and is 20 by 130 arcseconds in size. [23]
Each November, the Andromedids meteor shower appears to radiate from Andromeda. [66] The shower peaks in mid-to-late November every year, but has a low peak rate of fewer than 2 meteors per hour. [67] Astronomers have often associated the Andromedids with Biela's Comet, which was destroyed in the 19th century, but that connection is disputed. [68] 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. [69] Andromedid meteors sometimes appear as red fireballs. [70] [71] 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. [68] [72] 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. [73]
Aries is one of the constellations of the zodiac. It is located in the Northern celestial hemisphere between Pisces to the west and Taurus to the east. The name Aries is Latin for ram. Its old astronomical symbol is (♈︎). It is one of the 48 constellations described by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations. It is a mid-sized constellation ranking 39th in overall size, with an area of 441 square degrees.
Boötes is a constellation in the northern sky, located between 0° and +60° declination, and 13 and 16 hours of right ascension on the celestial sphere. The name comes from Latin: Boōtēs, which comes from Greek: Βοώτης, translit. Boṓtēs 'herdsman' or 'plowman'.
Corona Australis is a constellation in the Southern Celestial Hemisphere. Its Latin name means "southern crown", and it is the southern counterpart of Corona Borealis, the northern crown. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. The Ancient Greeks saw Corona Australis as a wreath rather than a crown and associated it with Sagittarius or Centaurus. Other cultures have likened the pattern to a turtle, ostrich nest, a tent, or even a hut belonging to a rock hyrax.
Grus is a constellation in the southern sky. Its name is Latin for the crane, a type of bird. It is one of twelve constellations conceived by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman. Grus first appeared on a 35-centimetre-diameter (14-inch) celestial globe published in 1598 in Amsterdam by Plancius and Jodocus Hondius and was depicted in Johann Bayer's star atlas Uranometria of 1603. French explorer and astronomer Nicolas-Louis de Lacaille gave Bayer designations to its stars in 1756, some of which had been previously considered part of the neighbouring constellation Piscis Austrinus. The constellations Grus, Pavo, Phoenix and Tucana are collectively known as the "Southern Birds".
Hydrus is a small constellation in the deep southern sky. It was one of twelve constellations created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman and it first appeared on a 35-cm (14 in) diameter celestial globe published in late 1597 in Amsterdam by Plancius and Jodocus Hondius. The first depiction of this constellation in a celestial atlas was in Johann Bayer's Uranometria of 1603. The French explorer and astronomer Nicolas Louis de Lacaille charted the brighter stars and gave their Bayer designations in 1756. Its name means "male water snake", as opposed to Hydra, a much larger constellation that represents a female water snake. It remains below the horizon for most Northern Hemisphere observers.
Triangulum is a small constellation in the northern sky. Its name is Latin for "triangle", derived from its three brightest stars, which form a long and narrow triangle. Known to the ancient Babylonians and Greeks, Triangulum was one of the 48 constellations listed by the 2nd century astronomer Ptolemy. The celestial cartographers Johann Bayer and John Flamsteed catalogued the constellation's stars, giving six of them Bayer designations.
Tucana is a constellation in the southern sky, named after the toucan, a South American bird. It is one of twelve constellations conceived in the late sixteenth century by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman. Tucana first appeared on a 35-centimetre-diameter (14 in) celestial globe published in 1598 in Amsterdam by Plancius and Jodocus Hondius and was depicted in Johann Bayer's star atlas Uranometria of 1603. French explorer and astronomer Nicolas Louis de Lacaille gave its stars Bayer designations in 1756. The constellations Tucana, Grus, Phoenix and Pavo are collectively known as the "Southern Birds".
Triangulum Australe is a small constellation in the far Southern Celestial Hemisphere. Its name is Latin for "the southern triangle", which distinguishes it from Triangulum in the northern sky and is derived from the acute, almost equilateral pattern of its three brightest stars. It was first depicted on a celestial globe as Triangulus Antarcticus by Petrus Plancius in 1589, and later with more accuracy and its current name by Johann Bayer in his 1603 Uranometria. The French explorer and astronomer Nicolas Louis de Lacaille charted and gave the brighter stars their Bayer designations in 1756.
Telescopium is a minor constellation in the southern celestial hemisphere, one of twelve named in the 18th century by French astronomer Nicolas-Louis de Lacaille and one of several depicting scientific instruments. Its name is a Latinized form of the Greek word for telescope. Telescopium was later much reduced in size by Francis Baily and Benjamin Gould.
Phoenix is a minor constellation in the southern sky. Named after the mythical phoenix, it was first depicted on a celestial atlas by Johann Bayer in his 1603 Uranometria. The French explorer and astronomer Nicolas Louis de Lacaille charted the brighter stars and gave their Bayer designations in 1756. The constellation stretches from roughly −39° to −57° declination, and from 23.5h to 2.5h of right ascension. The constellations Phoenix, Grus, Pavo and Tucana, are known as the Southern Birds.
Perseus is a constellation in the northern sky, named after the Greek mythological hero Perseus. It is one of the 48 ancient constellations listed by the 2nd-century astronomer Ptolemy, and among the 88 modern constellations defined by the International Astronomical Union (IAU). It is located near several other constellations named after ancient Greek legends surrounding Perseus, including Andromeda to the west and Cassiopeia to the north. Perseus is also bordered by Aries and Taurus to the south, Auriga to the east, Camelopardalis to the north, and Triangulum to the west. Some star atlases during the early 19th century also depicted Perseus holding the disembodied head of Medusa, whose asterism was named together as Perseus et Caput Medusae; however, this never came into popular usage.
Auriga is a constellation in the northern celestial hemisphere. It is one of the 88 modern constellations; it was among the 48 constellations listed by the 2nd-century astronomer Ptolemy. Its name is Latin for '(the) charioteer', associating it with various mythological beings, including Erichthonius and Myrtilus. Auriga is most prominent during winter evenings in the northern Hemisphere, as are five other constellations that have stars in the Winter Hexagon asterism. Because of its northern declination, Auriga is only visible in its entirety as far south as -34°; for observers farther south it lies partially or fully below the horizon. A large constellation, with an area of 657 square degrees, it is half the size of the largest, Hydra.
Circinus is a small, faint constellation in the southern sky, first defined in 1756 by the French astronomer Nicolas-Louis de Lacaille. Its name is Latin for compass, referring to the drafting tool used for drawing circles. Its brightest star is Alpha Circini, with an apparent magnitude of 3.19. Slightly variable, it is the brightest rapidly oscillating Ap star in the night sky. AX Circini is a Cepheid variable visible with the unaided eye, and BX Circini is a faint star thought to have been formed from the merger of two white dwarfs. Two sun-like stars have planetary systems: HD 134060 has two small planets, and HD 129445 has a Jupiter-like planet. Supernova SN 185 appeared in Circinus in 185 AD and was recorded by Chinese observers. Two novae have been observed more recently, in the 20th century.
Musca is a small constellation in the deep southern sky. It was one of 12 constellations created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman, and it first appeared on a celestial globe 35 cm (14 in) in diameter published in 1597 in Amsterdam by Plancius and Jodocus Hondius. The first depiction of this constellation in a celestial atlas was in Johann Bayer's Uranometria of 1603. It was also known as Apis for 200 years. Musca remains below the horizon for most Northern Hemisphere observers.
Leo Minor is a small and faint constellation in the northern celestial hemisphere. Its name is Latin for "the smaller lion", in contrast to Leo, the larger lion. It lies between the larger and more recognizable Ursa Major to the north and Leo to the south. Leo Minor was not regarded as a separate constellation by classical astronomers; it was designated by Johannes Hevelius in 1687.
Pegasus is a constellation in the northern sky, named after the winged horse Pegasus in Greek mythology. It was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and is one of the 88 constellations recognised today.
Pavo is a constellation in the southern sky whose name is Latin for 'peacock'. Pavo first appeared on a 35-cm (14 in) diameter celestial globe published in 1598 in Amsterdam by Petrus Plancius and Jodocus Hondius and was depicted in Johann Bayer's star atlas Uranometria of 1603, and was likely conceived by Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman. French explorer and astronomer Nicolas-Louis de Lacaille gave its stars Bayer designations in 1756. The constellations Pavo, Grus, Phoenix and Tucana are collectively known as the "Southern Birds".
SN 1885A was a supernova in the Andromeda Galaxy, the only one seen in that galaxy so far by astronomers. It was the first supernova ever seen outside the Milky Way, though it was not known at the time how far away it was. It is also known as "Supernova 1885".
NGC 515, also occasionally referred to as PGC 5201 or UGC 956, is a lenticular galaxy located approximately 228 million light-years from the Solar System in the constellation Pisces. It was discovered on 13 September 1784 by astronomer William Herschel.
NGC 517, also occasionally referred to as PGC 5214 or UGC 960, is a lenticular galaxy located approximately 188 million light-years from the Solar System in the constellation Pisces. It was discovered on 13 September 1784 by astronomer William Herschel.
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