Astronomy:Alpha Comae Berenices

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Short description: Star in the constellation Coma Berenices
Alpha Comae Berenices
Map of the constellation Coma Berenices
Location of α Comae Berenices (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Coma Berenices
Right ascension  13h 09m 59.285s[1]
Declination +17° 31′ 46.04″[1]
Apparent magnitude (V) 4.29 to 4.35
(combined)[2]
A: 4.85 / B: 5.53[3]
Characteristics
Spectral type A: F5V / B: F5V
(binary star)[4]
U−B color index −0.06[5]
B−V color index 0.45[5]
V−R color index 0.2[6]
R−I color index 0.2[6]
Astrometry
Radial velocity (Rv)−17.7±0.9[6] km/s
Proper motion (μ) RA: −433.13±0.70[1] mas/yr
Dec.: 141.24±0.51[1] mas/yr
Parallax (π)56.10 ± 0.89[1] mas
Distance58.1 ± 0.9 ly
(17.8 ± 0.3 pc)
Absolute magnitude (MV)3.82[7]
Orbit[8]
Period (P)25.8696±0.008219 yr
Semi-major axis (a)0.67144±0.00033″
Eccentricity (e)0.51060±0.00061
Inclination (i)90.0501±0.0062°
Longitude of the node (Ω)12.2272±0.0098°
Periastron epoch (T)57056.84±0.36
Argument of periastron (ω)
(secondary)		100.563±0.026°
Details
A
Mass1.237[9] M☉
Luminosity1.72[10] L☉
Surface gravity (log g)4.19[11] cgs
Temperature6,365[11] K
Metallicity [Fe/H]−0.23[11] dex
B
Mass1.087[9] M☉
Luminosity1.75[10] L☉
Temperature6,378[10] K
Other designations
Diadem, α Com, 42 Com, BD+18 2697, GC 17833, GJ 501, HIP 64241, SAO 100443, PPM 129630, ADS 8804, CCDM J13100+1732, WDS J13100+1732, LTT 13802, NLTT 33105, STF 1728, IDS 13051+1803 AB[6]
A: HD 114378, HR 4968[12]
B: HD 114379, HR 4969[13]
Database references
SIMBADThe system
A
B

Alpha Comae Berenices is a binary star system in the northern constellation of Coma Berenices (Berenice's Hair). Its name is a Bayer designation, which is Latinized from α Comae Berenices. With a combined apparent visual magnitude that varies 4.29 to 4.35, it is faintly visible to the naked eye. Based on parallax measurements, it is located at a distance of 58 light-years (17.8 pc) from the Earth.

This system consists of two main sequence stars, each a little hotter and more luminous than the Sun. The two components are designated Alpha Comae Berenices A and B. Component A is officially named Diadem /ˈdaɪədɛm/, the traditional name for the system.[14]

Nomenclature

α Comae Berenices (Latinised to Alpha Comae Berenices) is the system's Bayer designation, abbreviated Alpha Com or α Com. 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 systems, and adopted by the International Astronomical Union (IAU).[15] Alpha Comae Berenices is said to represent the crown worn by Queen Berenice.

The system has the proper name Diadem, of unknown modern origin.[4] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[16] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[17] 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.[14]

In Chinese, 太微左垣 (Tài Wēi Zuǒ Yuán), 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.[18] Consequently, the Chinese name for Alpha Comae Berenices itself is 太微左垣五 (Tài Wēi Zuǒ Yuán wǔ, English: the Fifth Star of Left Wall of Supreme Palace Enclosure),[19] representing 東上將 (Dōngshǎngjiāng), meaning The First Eastern General.[20] 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".[21]

Properties

Although Alpha Comae Berenices bears the title "alpha", at magnitude 4.32 it is actually fainter than Beta Comae Berenices.

This is a binary star, with almost equal components of magnitudes 5.05 m and 5.08 m orbiting each other with a period of 25.87 years. The system, estimated to be 58 light-years distant, is aligned nearly "edge-on" from the Earth so that the two stars appear to move back-and-forth in a straight line with a maximum separation of only 0.7 arcsec. The mean physical separation between them is approximately 10 AU, about the distance between the Sun and Saturn.

Eclipses are predicted to occur between the two components, however they have not been successfully observed due to miscalculations of the time of eclipse. If eclipses do occur, the next primary eclipse is expected to be around 27 September 2040; the most recent date for a secondary eclipse, which had only a 3.3% probability of happening, was 11 January 2026.[8]

The binary star has a visual companion, CCDM J13100+1732C, of apparent magnitude 10.2, located 89 arcseconds away along a position angle of 345°.[22]

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

  1. ↑ 1.0 1.1 1.2 1.3 van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V. http://www.aanda.org/articles/aa/abs/2007/41/aa8357-07/aa8357-07.html.  Vizier catalog entry
  2. ↑ "NSV 6116, database entry". New Catalogue of Suspected Variable Stars, the improved version. Moscow, Russia: Sternberg Astronomical Institute. 
  3. ↑ "Entry 13100+1732". Sixth Catalog of Orbits of Visual Binary Stars. United States Naval Observatory. April 24, 2005. http://ad.usno.navy.mil/wds/orb6/orb6orbits.txt. 
  4. ↑ 4.0 4.1 "Diadem". STARS. May 11, 2008. http://stars.astro.illinois.edu/sow/diadem.html. 
  5. ↑ 5.0 5.1 Hoffleit, D.; Warren, Jr., W. H.. "HR 4968, database entry". The Bright Star Catalogue. CDS. ID V/50. http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=V/50/catalog&recno=4968. 
  6. ↑ 6.0 6.1 6.2 6.3 "alf com". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=alf+com. 
  7. ↑ Reiners, Ansgar (January 2006), "Rotation- and temperature-dependence of stellar latitudinal differential rotation", Astronomy and Astrophysics 446 (1): 267–277, doi:10.1051/0004-6361:20053911, Bibcode: 2006A&A...446..267R 
  8. ↑ 8.0 8.1 Muterspaugh, Matthew W. et al. (2015). "Predicting the α Comae Berenices Time of Eclipse: How 3 Ambiguous Measurements out of 609 Caused a 26 Year Binary's Eclipse to be Missed". The Astronomical Journal 150 (5): 140. doi:10.1088/0004-6256/150/5/140. Bibcode: 2015AJ....150..140M. 
  9. ↑ 9.0 9.1 Pavlovic, R.; Todorovic, N. (2005). "Orbits of Seven Edge-On Visual Double Stars". Serbian Astronomical Journal 170 (170): 73–78. doi:10.2298/SAJ0570073P. Bibcode: 2005SerAJ.170...73P. 
  10. ↑ 10.0 10.1 10.2 Ten Brummelaar, Theo et al. (2000). "Binary Star Differential Photometry Using the Adaptive Optics System at Mount Wilson Observatory". The Astronomical Journal 119 (5): 2403. doi:10.1086/301338. Bibcode: 2000AJ....119.2403T. 
  11. ↑ 11.0 11.1 11.2 Soubiran, Caroline et al. (2016). "The PASTEL catalogue: 2016 version". Astronomy and Astrophysics 591: A118. doi:10.1051/0004-6361/201628497. Bibcode: 2016A&A...591A.118S. 
  12. ↑ "HD 114378". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+114378. 
  13. ↑ "HD 114379". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+114379. 
  14. ↑ 14.0 14.1 "Naming Stars". IAU.org. https://www.iau.org/public/themes/naming_stars/. 
  15. ↑ Hessman, F. V.; et al. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
  16. ↑ "International Astronomical Union | IAU". https://www.iau.org/science/scientific_bodies/working_groups/280/. 
  17. ↑ "WG Triennial Report (2015-2018) - Star Names". p. 5. https://www.iau.org/static/science/scientific_bodies/working_groups/280/wg-starnames-triennial-report-2015-2018.pdf. 
  18. ↑ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  19. ↑ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 , Hong Kong Space Museum. Accessed on line November 23, 2010.
  20. ↑ (in Chinese) English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name , Hong Kong Space Museum. Accessed on line November 23, 2010.
  21. ↑ Allen, Richard Hinckley (1963). "Coma Berenices". Star Names — Their Lore and Meaning. https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Coma_Berenices*.html. 
  22. ↑ Entry 13100+1732, discoverer code STF1728, components AB-C, The Washington Double Star Catalog , United States Naval Observatory. Accessed on line September 3, 2008.

Coordinates: Sky map 13h 09m 59.285s, +17° 31′ 46.04″



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