Alpha Comae Berenices (α Comae Berenices, abbreviated Alpha Com, α Com) is a

binary star A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved as separate stars us ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

Coma Berenices Coma Berenices is an ancient asterism in the northern sky, which has been defined as one of the 88 modern constellations. It is in the direction of the fourth galactic quadrant, between Leo and Boötes, and it is visible in both hemispher ...

( Berenice's Hair), away. It consists of two

main sequence In astronomy, the main sequence is a classification of stars which appear on plots of stellar color index, color versus absolute magnitude, brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or d ...

stars, each a little hotter and more luminous than the Sun. Alpha Comae Berenices is said to represent the crown worn by Queen Berenice. The two components are designated Alpha Comae Berenices A (officially named Diadem , the traditional name for the system) and B.

Nomenclature

''α Comae Berenices'' ( Latinised to ''Alpha Comae Berenices'') is the system's

Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek alphabet, Greek or Latin letter followed by the genitive case, genitive form of its parent constellation's Latin name. The original list of Bayer design ...

. The designations of the two components as ''Alpha Comae Berenices A'' and ''B'' derive from the convention used by the Washington Multiplicity Catalog (WMC) for

multiple star system A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. It may sometimes be used to refer to a single star. A large group of stars bound by gravitation is generally called a ''st ...

s, and adopted by the

International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

(IAU). The system bore the traditional names ''Diadem'' and ''Al Dafirah,'' the latter derived from the Arabic الضفيرة ''ađ̧-đ̧afīrah'' "the braid". In 2016, the

organized a

Working Group on Star Names The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize proper names for stars for the international astronomical community. It operates under Division C – Education ...

(WGSN) to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name ''Diadem'' for the component Alpha Comae Berenices A on 1 February 2017 and it is now so included in the List of IAU-approved Star Names. In Chinese, (), meaning '' Left Wall of Supreme Palace Enclosure'', refers to an asterism consisting of Alpha Comae Berenices, Eta Virginis, Gamma Virginis, Delta Virginis and Epsilon Virginis. Consequently, the

Chinese name Chinese may refer to: * Something related to China * Chinese people, people identified with China, through nationality, citizenship, and/or ethnicity **Han Chinese, East Asian ethnic group native to China. **'' Zhonghua minzu'', the supra-ethni ...

for Alpha Comae Berenices itself is (, .), representing (), meaning ''The First Eastern General''. 東上將 (Dōngshǎngjiāng), westernized into ''Shang Tseang'', but that name was designated for "v Comae Berenices" by R.H. Allen and the meaning is "a Higher General".Richard Hinckley Allen: Star Names — Their Lore and Meaning: Coma Berenices
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Properties

Although Alpha Comae Berenices bears the title "

alpha Alpha (uppercase , lowercase ) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter ''aleph'' , whose name comes from the West Semitic word for ' ...

", at

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

4.32 it is actually fainter than Beta Comae Berenices. It is a

, with almost equal components of magnitudes 5.05 m and 5.08 m

orbit In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...

ing each other with a period of 25.87 years. The system, estimated to be 58

light-years A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astro ...

distant, appears so nearly "edge-on" from the Earth that the two stars appear to move back-and-forth in a straight line with a maximum separation of only 0.7 arcsec. Eclipses are predicted to occur between the two components however they have not been successfully observed due to miscalculations of the time of eclipse. The mean separation between them is approximately 10 AU, about the distance between the Sun and

Saturn Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth the average density of Earth, but is over 95 tim ...

. The binary star has a visual companion, CCDM J13100+1732C, of apparent magnitude 10.2, located 89

arcsecond A minute of arc, arcminute (abbreviated as arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of a degree. Since one degree is of a turn, or complete rotation, one arcminute is of a tu ...

s away along a position angle of 345°.Entry 13100+1732, discoverer code STF1728, components AB-C
The Washington Double Star Catalog
,

United States Naval Observatory The United States Naval Observatory (USNO) is a scientific and military facility that produces geopositioning, navigation and timekeeping data for the United States Navy and the United States Department of Defense. Established in 1830 as the ...

. Accessed on line September 3, 2008. Alpha Comae Berenicis forms an isosceles triangle with globular star clusters Messier 53 and NGC 5053. The apparent diameter of this triangle is a little more than one degree. The location of Alpha Comae Berenicis is westward (preceding) of both globular star clusters.

References

External links

{{DEFAULTSORT:Alpha Comae Berenices Comae Berenices, Alpha Binary stars Coma Berenices F-type main-sequence stars

Diadem A diadem is a Crown (headgear), crown, specifically an ornamental headband worn by monarchs and others as a badge of Monarch, royalty. Overview The word derives from the Ancient Greek, Greek διάδημα ''diádēma'', "band" or "fillet", fro ...

Comae Berenices, 42 114378 064241 Triple stars BD+18 2697 0501 4968