23 Comae Berenices

23 Comae Berenices is a binary star[7] system in the northern constellation of Coma Berenices, situated a few degrees away from the North Galactic Pole.[11] It is visible to the naked eye as a faint, white-hued point of light with an apparent visual magnitude of 4.80.[2] The system is located around 310 light years away from the Sun, based on parallax.[1] It is moving closer to the Earth with a heliocentric radial velocity of −16 km/s.[6]

23 Comae Berenices
Observation data
Epoch J2000      Equinox J2000
Constellation Coma Berenices
Right ascension 12h 34m 51.08058s[1]
Declination +22° 37′ 45.3303″[1]
Apparent magnitude (V) 4.80[2] (4.96 + 6.90)[3]
Characteristics
Evolutionary stage A0IV[4]
U−B color index −0.01[5]
B−V color index +0.012±0.015[2]
Astrometry
Radial velocity (Rv)−16.0±1.8[6] km/s
Proper motion (μ) RA: −58.89[1] mas/yr
Dec.: 28.31[1] mas/yr
Parallax (π)10.52 ± 0.52[1] mas
Distance310 ± 20 ly
(95 ± 5 pc)
Absolute magnitude (MV)−0.08[2]
Orbit[7]
Period (P)33.04 yr
Semi-major axis (a)0.219″
Eccentricity (e)0.898
Inclination (i)109.7°
Longitude of the node (Ω)24.3°
Periastron epoch (T)B1964.62
Argument of periastron (ω)
(secondary)		214.5°
Details
Mass2.15[8] M☉
Radius3.0[9] R☉
Luminosity104.00[2] L☉
Surface gravity (log g)3.85[8] cgs
Temperature9,675±329[8] K
Rotational velocity (v sin i)40[8] km/s
Age210[8] Myr
Other designations
23 Com, BD+23°2475, FK5 1323, GC 17142, HD 109485, HIP 61394, HR 4789, SAO 82390, WDS J12349+2238[10]
Database references
SIMBADdata

The components of this system orbit each other with a period of 33 years, a large eccentricity of 0.9, and an angular semimajor axis of 0.219″.[7] The primary, designated component A, is a magnitude 4.96[3] star with a stellar classification of A0IV,[4] matching an A-type subgiant that has exhausted the supply of hydrogen at its core and is in the process of evolving into a giant. Bychkov et al. (2009) list it as an Am star with an average field strength of 26×10−4 T.[12]

The primary is 210[8] million years old and is spinning with a projected rotational velocity of 40 km/s.[8] It has 2.15[8] times the mass of the Sun and about three[9] times the Sun's radius. The star is radiating 104[2] times the luminosity of the Sun from its photosphere at an effective temperature of 9,675 K.[8]

References
  1. van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  2. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  3. Malkov, O. Yu.; Tamazian, V. S.; Docobo, J. A.; Chulkov, D. A. (2012). "Dynamical Masses of a Selected Sample of Orbital Binaries". Astronomy and Astrophysics. 546: 5. Bibcode:2012A&A...546A..69M. doi:10.1051/0004-6361/201219774. A69.
  4. Cowley, A.; Cowley, C.; Jaschek, M.; Jaschek, C. (April 1969). "A study of the bright A stars. I. A catalogue of spectral classifications". Astronomical Journal. 74: 375–406. Bibcode:1969AJ.....74..375C. doi:10.1086/110819.
  5. Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  6. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  7. Seymour, Diana M.; Mason, Brian D.; Hartkopf, William I.; Wycoff, Gary L. (February 2002), "Binary Star Orbits. II. Preliminary First Orbits for 117 Systems", The Astronomical Journal, 123 (2): 1023–1038, Bibcode:2002AJ....123.1023S, doi:10.1086/338441.
  8. David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146.
  9. Pasinetti Fracassini, L. E.; et al. (February 2001). "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)". Astronomy and Astrophysics (Third ed.). 367 (2): 521–524. arXiv:astro-ph/0012289. Bibcode:2001A&A...367..521P. doi:10.1051/0004-6361:20000451.
  10. "23 Com". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 8 September 2012.
  11. Straizys, V.; Meistas, E. (1989). "Photoelectric photometry of bright stars in the vicinity of the North Galactic Pole". Vilnius Astronomijos Observatorijos Biuletenis. 84: 26. Bibcode:1989VilOB..84...26S.
  12. Bychkov, V. D.; et al. (2009), "Catalogue of averaged stellar effective magnetic fields - II. Re-discussion of chemically peculiar A and B stars", Monthly Notices of the Royal Astronomical Society, 394 (3): 1338, Bibcode:2009MNRAS.394.1338B, doi:10.1111/j.1365-2966.2008.14227.x.
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