Coma Berenices has been recognized as an asterism since the Hellenistic period[3] (or much earlier, according to some authors), and is the only modern constellation named for an historic figure.[4] It was introduced to Western astronomy during the third century BC by Conon of Samos, the court astronomer of Egyptian ruler Ptolemy III Euergetes, to honour Ptolemy's consort, Berenice II.[5] Berenice vowed to sacrifice her long hair as a votive offering if Ptolemy returned safely from battle during the Third Syrian War.[6] Modern scholars are uncertain if Berenice made the sacrifice before or after Ptolemy's return; it was suggested that it happened after Ptolemy's return (around March–June or May 245 BC), when Conon presented the asterism jointly with scholar and poet Callimachus during a public evening ceremony.[7] In Callimachus' poem, Aetia (composed around that time), Berenice dedicated her tresses "to all the gods". In Poem 66, the Latin translation by the Roman poet Catullus, and in Hyginus' De Astronomica, she dedicated her tresses to Aphrodite and placed them in the temple of Arsinoe II (identified after Berenice's death with Aphrodite) at Zephyrium. According to De astronomica, by the next morning the tresses had disappeared. Conon proposed that Aphrodite had placed the tresses in the sky as an acknowledgement of Berenice's sacrifice.[6] Callimachus called the asterism plokamos Berenikēs or bostrukhon Berenikēs in Greek, translated into Latin as "Coma Berenices" by Catullus. Hipparchus[8] and Geminus also recognized it as a distinct constellation.[9]Eratosthenes called it "Berenice's Hair" and "Ariadne's Hair", considering it part of the constellation Leo.[10] Similarly, Ptolemy did not include it among his 48 constellations in the Almagest;[8] considering it part of Leo[3] and calling it Plokamos.[11]
Coma Berenices became popular during the 16th century. In 1515, a set of gores by Johannes Schöner labelled the asterism Trica, "hair". In 1536 it appeared on a celestial globe by Caspar Vopel, who is credited with the asterism's designation as a constellation.[12] That year, it also appeared on a celestial map by Petrus Apianus as "Crines Berenices". In 1551, Coma Berenices appeared on a celestial globe by Gerardus Mercator with five Latin and Greek names: Cincinnus, caesaries, πλόκαμος, Berenicis crinis and Trica. Mercator's reputation as a cartographer ensured the constellation's inclusion on Dutch sky globes beginning in 1589.[13]
Tycho Brahe, also credited with Coma's designation as a constellation, included it in his 1602 star catalogue.[3] Brahe recorded fourteen stars in the constellation; Johannes Hevelius increased its number to twenty-one, and John Flamsteed to forty-three. Coma Berenices also appeared in Johann Bayer's 1603 Uranometria, and a few other 17th-century celestial maps followed suit. Coma Berenices and the now-obsolete Antinous are considered the first post-Ptolemaic constellations depicted on a celestial globe.[14] With Antinous, Coma Berenices exemplified a trend in astronomy in which globe- and map-makers continued to rely on the ancients for data. This trend ended at the turn of the 16th century with observations of the southern sky and the work of Tycho Brahe.[13]
Before the 18th century Coma Berenices was known in English by several names, including "Berenice's Bush" and "Berenice's periwig".[15] The earliest-known English name, "Berenices haire", dates to 1601.[15][16] By 1702 the constellation was known as Coma Berenices,[17] and appears as such in the 1731 Universal Etymological English Dictionary.
Non-Western astronomy
Coma Berenices was known to the Akkadians as Ḫegala.[18] In Babylonian astronomy a star, known as ḪÉ.GÁL-a-a (translated as "which is before it") or MÚL.ḪÉ.GÁL-a-a, is tentatively considered part of Coma Berenices.[19] It was also argued that Coma Berenices appears in Egyptian Ramesside star clocks as sb3w ꜥš3w, meaning "many stars".[20]
In Arabic astronomy Coma Berenices was known as Al-Dafira الضفيرة ("braid"),Al-Hulbaالهلبة and Al-Thu'aba الذؤابة (both meaning "tuft"), the latter two are translations of the Ptolemaic Plokamos, forming the tuft of the constellation Leo[11] and including most of the Flamsteed-designated stars (particularly 12, 13, 14, 16, 17, 18 and 21 Comae Berenices).[21]Al-Sufi included it in Leo. Ulugh Beg, however, regarded Al-Dafira as consisting of two stars, 7 and 23 Comae Berenices.[22]
The North American Pawnee people depicted Coma Berenices as ten faint stars on a tanned elk-skin star map dated to at least the 17th century.[23] In the South American Kalina mythology, the constellation was known as ombatapo (face).[24]
The constellation was also recognized by several Polynesian peoples. The people of Tonga had four names for Coma Berenices: Fatana-lua, Fata-olunga, Fata-lalo and Kapakau-o-Tafahi.[25] The Boorong people called the constellation Tourt-chinboiong-gherra, and saw it as a small flock of birds drinking rainwater from a puddle in the crotch of a tree.[26] The people of the Pukapuka atoll may have called it Te Yiku-o-te-kiole, although sometimes this name is associated with Ursa Major.[27]
Characteristics
Coma Berenices is bordered by Boötes to the east, Canes Venatici to the north, Leo to the west and Virgo to the south. Covering 386.5 square degrees and 0.937% of the night sky, it ranks 42nd of the 88 constellations by area.[28] The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "Com".[29] The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930,[b] are defined by a polygon of 12 segments (illustrated in infobox). In the equatorial coordinate system, the right ascension coordinates of these borders lie between 11h 58m 25.09s and 13h 36m 06.94s, and the declination coordinates are between +13.30° and +33.31°.[1] Coma Berenices is wholly visible to observers north of latitude 56°S.[c] and the constellation's midnight culmination occurs on 2 April.[31]
Coma Berenices is not particularly bright, as none of its stars are brighter than fourth magnitude,[32] although there are 66 stars brighter than or equal to apparent magnitude 6.5.[d][28]
The second-brightest star in Coma Berenices is the 4.3-magnitude, bluish Alpha Comae Berenices (42 Comae Berenices), with the proper name Diadem,[38] in the southeastern part of the constellation. Despite its Alpha Bayer designation, the star is dimmer than Beta Comae Berenices, being one of the cases where designation does not correspond to the brightest star. It is a double star, with the spectral classes of F5V and F6V.[39] The star system is 58.1 ± 0.9 light-years from Earth.[40]
Gamma Comae Berenices (15 Comae Berenices) is an orange-hued giant star with a magnitude of 4.4 and a spectral class of K1III C. In the southwestern part of the constellation, it is 169 ± 2 light-years from Earth,[41] Estimated to be around 1.79 times as massive as the Sun,[42] it has expanded to around 10 times its radius.[43] It is the brightest star in the Coma Star Cluster.[44] With Alpha Comae Berenices and Beta Comae Berenices, Gamma Comae Berenices forms a 45-degree isosceles triangle from which Berenice's imaginary tresses hang.
A number of supernovae have been discovered in Coma Berenices. Four (SN 1940B, SN 1969H, SN 1987E and SN 1999gs) were in the NGC 4725 galaxy,[62] and another four were discovered in the M99 galaxy (NGC 4254): SN 1967H, SN 1972Q, SN 1986I and SN 2014L.[62] Five were discovered in the M100 galaxy (NGC 4321): SN 1901B, SN 1914A, SN 1959E, SN 1979C and SN 2006X.[62] SN 1940B, discovered on 5 May 1940, was the first observed type II supernova.[63]SN 2005ap, discovered on 3 March 2005, is the second-brightest-known supernova to date with a peak absolute magnitude of about −22.7.[64] Due to its great distance from Earth (4.7 billion light-years), it was not visible to the naked eye and was discovered telescopically. SN 1979C, discovered in 1979, retained its original X-ray brightness for 25 years despite fading in visible light.[65]
Coma Berenices has seven known exoplanets.[71] One, HD 108874 b, has Earth-like insolation.[72]WASP-56 is a sun-like star of spectral type G6 and apparent magnitude 11.48 with a planet 0.6 the mass of Jupiter that has a period of 4.6 days.[73]
Star clusters
Coma Star Cluster
The Coma Star Cluster represents Berenice's sacrificed tresses and as a naked eye object has been known since antiquity, appearing in Ptolemy's Almagest.[74] It doesn't have a Messier or NGC designation, but is in the Melotte catalogue of open clusters (designated Melotte 111) and is also catalogued as Collinder 256. It is a large, diffuse open cluster of about 50 stars ranging between magnitudes five and ten, including several of Coma Berenices' stars which are visible to the naked eye. The cluster is spread over a huge region (more than five degrees across) near Gamma Comae Berenices. It has such a large apparent size because it is relatively close, only 280 light-years or 86 parsecs away.[75][76]
Globular clusters
M53 (NGC 5024) is a globular cluster which was discovered independently by Johann Elert Bode in 1775 and Charles Messier in February 1777; William Herschel was the first to resolve it into stars.[57] The magnitude-7.7 cluster is 56,000 light-years from Earth. Only 1° away is NGC 5053, a globular cluster with a sparser nucleus of stars. Its total luminosity is the equivalent of about 16,000 suns, one of the lowest luminosities of any globular cluster. It was discovered by William Herschel in 1784. NGC 4147 is a somewhat dimmer globular cluster, with a much-smaller apparent size and an apparent magnitude of 10.7.[77]
Galaxies
Coma Supercluster
The Coma Supercluster, itself part of the Coma Filament, contains the Coma and Leo Cluster of galaxies. The Coma Cluster (Abell 1656) is 230 to 300 million light-years away. It is one of the largest-known clusters, with at least 10,000 galaxies (mainly elliptical, with a few spiral galaxies).[78] Due to its distance from Earth, most of the galaxies are visible only through large telescopes. Its brightest members are NGC 4874 and NGC 4889, both with a magnitude of 13; most others are magnitude 15 or dimmer. NGC 4889 is a giant elliptical galaxy with one of the largest-known black holes (21 billion solar masses),[79] and NGC 4921 is the cluster's brightest spiral galaxy.[80] After observing the Coma Cluster, astronomer Fritz Zwicky first postulated the existence of dark matter during the 1930s.[78] The massive galaxy Dragonfly 44 discovered in 2015 was found to consist almost entirely of dark matter.[81] Its mass is very similar to that of the Milky Way,[81] but it emits only 1% of the light emitted by the Milky Way.[82] NGC 4676, sometimes called the Mice Galaxies, is a pair of interacting galaxies 300 million light-years from Earth. Its progenitor galaxies were spiral, and astronomers estimate that they had their closest approach about 160 million years ago. That approach triggered large regions of star formation in both galaxies, with long "tails" of dust, stars and gas. The two progenitor galaxies are predicted to interact significantly at least one more time before they merge into a larger, probably-elliptical galaxy.[83]
Virgo Cluster
Coma Berenices contains the northern portion of the Virgo Cluster (also known as the Coma–Virgo Cluster), about 60 million light-years away. The portion includes six Messier galaxies. M85 (NGC 4382), considered elliptical or lenticular, is one of the cluster's brighter members at magnitude nine. M85 is interacting with the spiral galaxy NGC 4394 and the elliptical galaxy MCG-3-32-38.[66] However, it is relatively isolated from the rest of the cluster.[85]M88 (NGC 4501) is a multi-arm spiral galaxy seen at about 30° from edge-on. It has a highly-regular shape with well-developed, symmetrical arms. Among the first galaxies recognized as spiral,[86] it has a supermassive black hole in its center.[66]M91 (NGC 4548), a barred spiral galaxy with a bright, diffuse nucleus, is the faintest object in Messier's catalog at magnitude 10.2.[87]M98 (NGC 4192), a bright, elongated spiral galaxy seen nearly edge-on, appears elliptical because of its unusual angle. The magnitude-10 galaxy has no redshift.[88]M99 (NGC 4254) is a spiral galaxy seen face-on. Like M98 it is of magnitude-10 and has an unusually long arm on its west side. Four supernovae have been observed in the galaxy.[89][90][91]M100 (NGC 4321), a magnitude-nine spiral galaxy seen face-on, is one of the cluster's brightest.[59] Photographs reveal a brilliant core, two prominent spiral arms, an array of secondary arms and several dust lanes.
Other galaxies
M64 (NGC 4826) is known as the Black Eye Galaxy because of the prominent dark dust lane in front of the galaxy's bright nucleus. Also known as the Sleeping Beauty and Evil Eye galaxy,[92] it is about 17.3 million light-years away.[93] Recent studies indicate that the interstellar gas in the galaxy's outer regions rotates in the opposite direction from that in the inner regions, leading astronomers to believe that at least one satellite galaxycollided with it less than a billion years ago. All other evidence of the smaller galaxy has been assimilated. At the interface between the clockwise- and counterclockwise-rotating regions are many new nebulae and young stars.[83]
NGC 4314 is a face-on barred spiral galaxy at a distance of 40 million light-years. It is unique for its region of intense star formation, creating a ring around its nucleus which was discovered by the Hubble Space Telescope. The galaxy's prodigious star formation began five million years ago, in a region with a diameter of 1,000 light-years. The core's structure is also unique because the galaxy has spiral arms which feed gas into the bar.[83]
NGC 4565 is an edge-on spiral galaxy which appears superimposed on the Virgo Cluster. NGC 4565 has been nicknamed the Needle Galaxy because when seen in full, it appears as a narrow streak of light.[95] Like many edge-on spiral galaxies, it has a prominent dust lane and a central bulge. NGC 4565 has at least two satellite galaxies, and one of them is interacting with it.[96]
NGC 4651, about the size of the Milky Way, has tidal stellar streams gravitationally stripped from a smaller, satellite galaxy.[97] It is about 62 million light-years away.[97] It is located on the outskirts of the cluster,[98] and is also known as the Umbrella Galaxy. Unlike the other spiral galaxies in the cluster, NGC 4651 is rich in neutral hydrogen, which also extends beyond the optical disk.[99] Its star formation is typical for a galaxy of its type.[98]
The constellation Coma Berenices hosts the galaxy NGC 4495 among myriad other astronomical objects.
The jellyfish galaxy JW39 hangs serenely in this image from the NASA/ESA Hubble Space Telescope. This galaxy lies over 900 million light-years away in the constellation Coma Berenices.
The Coma Berenicids meteor shower peaks around 18 January.[52] Despite the shower's low intensity (averaging one or two meteors per hour) its meteors are some of the fastest, with speeds up to 65 kilometres per second (40 mi/s).[52]
In culture
Since Callimachus' poem, Coma Berenices has been occasionally featured in culture. Alexander Pope alludes to the legend in the ending of The Rape of the Lock, in which the titular hair is placed among the stars. (The poem would go on to provide the names of some of the moons of Uranus.) In 1886, Spanish artist Luis Ricardo Falero created a mezzotint print personifying Coma Berenices alongside Virgo and Leo.[109] In 1892, the Russian poet Afanasy Fet made the constellation the subject of his short poem, composed for the Countess Natalya Sollogub.[110] The Swedish poet Gunnar Ekelöf wrote the lines "Your friend the comet combed his hair with the Leonids / Berenice let her hair hang down from the sky" in a 1933 poem.[111] American writer and folksinger Richard Fariña mentions Coma Berenices in his 1966 novel Been Down So Long It Looks Like Up To Me, sardonically writing about content typical to upper-level astronomy coursework at Cornell: "It's the advanced courses give you trouble. Relativity principles, spiral nebula in Coma Berenices, that kind of hassle". The Bolivian poet, Pedro Shimose, makes Coma Berenices the home address of his "Señorita NGC 4565" in his poem "Carta a una estrella que vive en otra constelación" ("Letter to a star who lives in another constellation"), included in his 1967 collection, "Sardonia".[112] "[113] The Irish poet W. B. Yeats, in his poem "Her Dream", refers to "Berenice's burning hair" being "nailed upon the night". Francisco Guerrero, a 20th-century Spanish composer, wrote an orchestral work on the constellation in 1996. In 1999 Irish artist Alice Maher made a series of four oversize drawings, entitled Coma Berenices, of entwining black hair coils.[114]
Notes
^One other constellation's name is derived from a reference to a historical person: the constellation Scutum is a shortening of the former name Scutum Sobiescianum ("shield of Sobieski"), named after King John III Sobieski of Poland. It is called the equivalent of "Shield of Sobieski" in some other languages, such as French.
^Delporte had proposed standardising the constellation boundaries to the International Astronomical Union, who had agreed and gave him the lead role[30]
^While parts of the constellation technically rise above the horizon to observers between 56°S and 77°S, stars within a few degrees of the horizon are to all intents and purposes unobservable.[28]
^Objects of magnitude 6.5 are among the faintest visible to the unaided eye in suburban–rural transition night skies.[33]
^Dekker, Elly (2012). Illustrating the Phaenomena: Celestial Cartography in Antiquity and the Middle Ages. Oxford, United Kingdom: Oxford University Press. p. 41. ISBN978-0-19-960969-7.
^Garfinkle, Robert (1997). Star-Hopping: Your Visa to Viewing the Universe. Cambridge, United Kingdom: Cambridge University Press. p. 122. ISBN0-521-59889-3.
^ abKunitzsch, Paul (2002). "Albumasariana"(PDF). Annali Istituto Universitario Orientale di Napoli. OPAR L'Orientale Open Archive. p. 4. Retrieved 6 November 2016.
^Ridpath, Ian. "Coma Berenices". Star Tales. Retrieved 11 April 2012.
^Leybourn, William; Morden, Robert (1702). An Introduction to Astronomy, Geography, Navigation and Other Mathematical Sciences, Made Easie by the Description and Uses of the Coelestial and Terrestrial Globes. R. Morden. p. 30.
^Douglas B. Miller; R. Mark Shipp (1996). An Akkadian Handbook: Paradigms, Helps, Glossary, Logograms, and Sign List. Eisenbrauns. p. 53. ISBN0-931464-86-2.
^"The Tail Hair". Two Deserts One Sky. Retrieved 6 November 2016.
^Royal Astronomical Society (1843). Memoirs of the Royal Astronomical Society. Vol. 14–15. p. 191.
^Ralph N. Buckstaff (1927). "Stars and Constellations of a Pawnee Sky Map". American Anthropologist. Vol. 29, no. 2. p. 282.
^Lévi-Strauss, Claude (1983). Mythologiques. University of Chicago Press. p. 232. ISBN0-226-47487-9.
^Maud Worcester Makemson (1941). The Morning Star Rises: an account of Polynesian astronomy. Yale University Press. p. 281. Bibcode:1941msra.book.....M.
^Helaine Selin, ed. (2012). Astronomy Across Cultures: The History of Non-Western Astronomy. Springer Science & Business Media. p. 75. ISBN978-94-011-4179-6.
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^Pierre de Ponthiere; Franz-Josef Hambsch; Kenneth Menzies; Richard Sabo (10 May 2016). "TU Comae Berenices : Blazhko RR Lyrae Star in a Potential Binary System". Journal of the American Association of Variable Star Observers (Jaavso). 44 (1): 18. arXiv:1605.03242. Bibcode:2016JAVSO..44...18D.
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^W. Lyra. Naming the extrasolar planets. INSPIRE / High-Energy Physics. p. 23.
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^Martin, N. F.; De Jong, J. T. A.; Rix, H. W. (2008). "A Comprehensive Maximum Likelihood Analysis of the Structural Properties of Faint Milky Way Satellites". The Astrophysical Journal. 684 (2): 1075–1092. arXiv:0805.2945. Bibcode:2008ApJ...684.1075M. doi:10.1086/590336. S2CID17838966.