# 12 Comae Berenices

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Star in the constellation Coma Berenices

12 Comae Berenices Location of 12 Comae Berenices (circled in red) Observation data Epoch J2000.0 Equinox J2000.0 Constellation Coma Berenices Right ascension 12h 22m 30.31076s[1] Declination +25° 50′ 46.1896″[1] Apparent magnitude (V) 4.80[2] Characteristics Spectral type G7 III + A3 V[3] U−B color index 0.47/0.09[2] B−V color index 0.82/0.11[2] Astrometry Radial velocity (Rv) +0.5±0.9[4] km/s Proper motion (μ) RA: −10.847[1] mas/yr Dec.: −9.546[1] mas/yr Parallax (π) 11.8280±0.2353 mas[1] Distance 276 ± 5 ly (85 ± 2 pc) Absolute magnitude (MV) 0.55±0.06 / 1.05±0.06[2] Orbit[3] Period (P) 396.4473±0.0002 d Semi-major axis (a) 20.3358±0.00066 Eccentricity (e) 0.599483±0.000026 Inclination (i) 64.8556±0.0011° Longitude of the node (Ω) 118.618±0.004° Periastron epoch (T) 46877.148±0.054 MJD Argument of periastron (ω) (primary) 100.162±0.001° Semi-amplitude (K1) (primary) 22.42±2.22 km/s Details 12 Com A Mass 2.64±0.07[3] M☉ Radius 8.36±0.15[3] R☉ Luminosity 56.2+2.7 −2.5[2] L☉ Temperature 5,300±200[2] K Age 533 ± 41 ± 42[3] Myr 12 Com B Mass 2.10±0.03[3] M☉ Radius 2.5±0.3[2] R☉ Luminosity 30.2+2.2 −2.2[2] L☉ Temperature 8,500±500[2] K Other designations 12 Com, NSV 5581, BD+26°2337, FK5 1318, HD 107700, HIP 60351, HR 4707, SAO 82273, WDS J12225+2551A[5] Database references SIMBAD data

12 Comae Berenices in optical light

**12 Comae Berenices** is a [binary star](/source/Binary_star) system in the northern [constellation](/source/Constellation) of [Coma Berenices](/source/Coma_Berenices). It is the brightest member of the [Coma Star Cluster](/source/Coma_Star_Cluster) and is visible to the naked eye with an [apparent visual magnitude](/source/Apparent_visual_magnitude) of 4.80.[2] Although listed as a suspected [variable star](/source/Variable_star), there is no [photometric](/source/Photometry_(astronomy)) evidence of it being variable in luminosity. However, the [radial velocity](/source/Radial_velocity) was found to be variable, as announced by [W. W. Campbell](/source/William_Wallace_Campbell) in 1910. The first orbital solution was published by [Vinter Hansen](/source/Julie_Vinter_Hansen) in the 1940s.[2] It is a double-lined [spectroscopic binary](/source/Spectroscopic_binary) with an [orbital period](/source/Orbital_period) of 396.5 days and an [eccentricity](/source/Orbital_eccentricity) of 0.566.[6]

This system consists of two [stars](/source/Star), an [evolved](/source/Stellar_evolution) [G-type](/source/G-type_star) [giant star](/source/Giant_star) and a smaller but higher temperature [A-type main-sequence star](/source/A-type_main-sequence_star).[7] Griffin and Griffin (2011) suggested that the secondary component may have begun its evolution away from the main sequence, and instead assigned it a [luminosity class](/source/Luminosity_class) of IV. The primary, designated component A, has about 2.6 times the [mass of the Sun](/source/Mass_of_the_Sun) and has expanded to 8.4 times the [Sun's radius](/source/Sun's_radius). It is radiating 56 times the [Sun's luminosity](/source/Sun's_luminosity) from its enlarged [photosphere](/source/Photosphere) at an [effective temperature](/source/Effective_temperature) of 5,300 K. Its companion, component B, has double the Sun's mass and 2.5 times the radius. It shines with 30 times the luminosity of the Sun at 8,500 K.[2]

## References

1. ^ [***a***](#cite_ref-GaiaDR2_1-0) [***b***](#cite_ref-GaiaDR2_1-1) [***c***](#cite_ref-GaiaDR2_1-2) [***d***](#cite_ref-GaiaDR2_1-3) [***e***](#cite_ref-GaiaDR2_1-4) [Brown, A. G. A.](/source/Anthony_Brown_(scientist)); et al. ([Gaia collaboration](/source/Data_Processing_and_Analysis_Consortium)) (August 2018). ["*Gaia* Data Release 2: Summary of the contents and survey properties"](https://doi.org/10.1051%2F0004-6361%2F201833051). *[Astronomy & Astrophysics](/source/Astronomy_%26_Astrophysics)*. **616**. A1. [arXiv](/source/ArXiv_(identifier)):[1804.09365](https://arxiv.org/abs/1804.09365). [Bibcode](/source/Bibcode_(identifier)):[2018A&A...616A...1G](https://ui.adsabs.harvard.edu/abs/2018A&A...616A...1G). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/201833051](https://doi.org/10.1051%2F0004-6361%2F201833051). [Gaia DR2 record for this source](https://vizier.u-strasbg.fr/viz-bin/VizieR-S?Gaia%20DR2%204008342726516877312) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-Griffin2011_2-0) [***b***](#cite_ref-Griffin2011_2-1) [***c***](#cite_ref-Griffin2011_2-2) [***d***](#cite_ref-Griffin2011_2-3) [***e***](#cite_ref-Griffin2011_2-4) [***f***](#cite_ref-Griffin2011_2-5) [***g***](#cite_ref-Griffin2011_2-6) [***h***](#cite_ref-Griffin2011_2-7) [***i***](#cite_ref-Griffin2011_2-8) [***j***](#cite_ref-Griffin2011_2-9) [***k***](#cite_ref-Griffin2011_2-10) [***l***](#cite_ref-Griffin2011_2-11) Griffin, R. E. M.; Griffin, R. F. (February 2011), "Composite spectra: XVII. 12 Comae, a member of the Coma open cluster", *Astronomische Nachrichten*, **332** (2): 105–115, [Bibcode](/source/Bibcode_(identifier)):[2011AN....332..105G](https://ui.adsabs.harvard.edu/abs/2011AN....332..105G), [doi](/source/Doi_(identifier)):[10.1002/asna.201011514](https://doi.org/10.1002%2Fasna.201011514)

1. ^ [***a***](#cite_ref-Lam_3-0) [***b***](#cite_ref-Lam_3-1) [***c***](#cite_ref-Lam_3-2) [***d***](#cite_ref-Lam_3-3) [***e***](#cite_ref-Lam_3-4) [***f***](#cite_ref-Lam_3-5) Lam, Rex; Sandquist, Eric L.; Schaefer, Gail H.; Farrington, Christopher D.; Monnier, John D.; Anugu, Narsireddy; Lanthermann, Cyprien; Klement, Robert; Ennis, Jacob; Setterholm, Benjamin R.; Gardner, Tyler; Kraus, Stefan; Davies, Claire L.; Orosz, Jerome A. (2023). ["Precise Age for the Binary Star System 12 Com in the Coma Berenices Cluster"](https://doi.org/10.3847%2F1538-3881%2Faccddb). *The Astronomical Journal*. **166** (1): 29. [arXiv](/source/ArXiv_(identifier)):[2304.07397](https://arxiv.org/abs/2304.07397). [Bibcode](/source/Bibcode_(identifier)):[2023AJ....166...29L](https://ui.adsabs.harvard.edu/abs/2023AJ....166...29L). [doi](/source/Doi_(identifier)):[10.3847/1538-3881/accddb](https://doi.org/10.3847%2F1538-3881%2Faccddb).

1. **[^](#cite_ref-rgcrv_4-0)** Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Batten, Alan Henry; Heard, John Frederick (eds.). *Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30*. Vol. 30. University of Toronto: [International Astronomical Union](/source/International_Astronomical_Union). p. 57. [Bibcode](/source/Bibcode_(identifier)):[1967IAUS...30...57E](https://ui.adsabs.harvard.edu/abs/1967IAUS...30...57E).

1. **[^](#cite_ref-SIMBAD_5-0)** ["12 Com"](http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=12+Com). *[SIMBAD](/source/SIMBAD)*. [Centre de données astronomiques de Strasbourg](/source/Centre_de_donn%C3%A9es_astronomiques_de_Strasbourg). Retrieved December 30, 2018.

1. **[^](#cite_ref-mermilliod2007_6-0)** Mermilliod, J. -C; et al. (2007). ["Red giants in open clusters. XIII. Orbital elements of 156 spectroscopic binaries"](https://doi.org/10.1051%2F0004-6361%3A20078007). *Astronomy and Astrophysics*. **473** (3): 829. [Bibcode](/source/Bibcode_(identifier)):[2007A&A...473..829M](https://ui.adsabs.harvard.edu/abs/2007A&A...473..829M). [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20078007](https://doi.org/10.1051%2F0004-6361%3A20078007).

1. **[^](#cite_ref-Abt2008_7-0)** Abt, Helmut A. (2008). ["Visual Multiples. IX. MK Spectral Types"](https://doi.org/10.1086%2F525529). *The Astrophysical Journal Supplement Series*. **176** (1): 216–217. [Bibcode](/source/Bibcode_(identifier)):[2008ApJS..176..216A](https://ui.adsabs.harvard.edu/abs/2008ApJS..176..216A). [doi](/source/Doi_(identifier)):[10.1086/525529](https://doi.org/10.1086%2F525529).

v t e Constellation of Coma Berenices List of stars in Coma Berenices Coma Berenices in Chinese astronomy Stars Bayer α (Diadem) β γ Flamsteed 7 11 12 13 14 16 17 21 23 (Phyllon Kissinou) 24 31 35 36 37 41 Variable FK GP IN LW HR 4668 HD 107146 108863 108874 110067 114762 b 115404 116029 Other 2MASS J12195156+3128497 KELT-6 WASP-56 WISE 1217+1626 Exoplanets HD 108874 b c KELT-6b Star clusters Coma Star Cluster Messier 53 NGC 4147 NGC 5053 Nebulae LoTr 5 Galaxies Messier 64 (Black Eye Galaxy) 85 88 91 98 99 100 NGC 4014 4015 4017 4053 4056 4060 4061 4065 4066 4070 4072 4074 4076 4084 4086 4089 4090 4091 4092 4093 4095 4098 4136 4146 4150 4162 4185 4189 4203 4211 4212 4213 4222 4237 4245 4253 4262 4274 4278 4293 4298 4302 4308 4310 4312 4314 4323 4328 4340 4359 4375 4383 4393 4394 4414 4419 4448 4450 4455 4459 4468 4473 4474 4475 4477 4479 4489 4494 4495 4498 4502 4506 4515 4516 4523 4525 4540 4555 4556 4558 4559 4561 4565 4571 4585 4595 4611 4614 4615 4633 4634 4651 4659 4670 4673 4676 (Mice Galaxies) 4689 4692 4710 4712 4725 4747 4839 4848 4860 4869 4871 4872 4873 4874 4875 4876 4881 4883 4886 4889 4892 4895 4907 4911 4919 4921 4944 5000 5004 5012 5032 5056 5172 Other 3C 275.1 3C 287 Arp 60 Coma Berenices Dragonfly 44 IC 755 (NGC 4019) IC 831 IC 860 IC 3505 IC 3528 IC 4040 IC 4051 IOK-1 IRAS F12032+1707 LEDA 83677 M85-HCC1 Malin 1 PGC 44691 PKS 1155+251 PKS 1222+216 VIRGOHI21 ZwCl 1305.4+2941 BCG Galaxy clusters Abell 1413 Coma I Coma Cluster Coma Supercluster M94 Group NGC 4065 Group NGC 4631 Group Astronomical events GRB 050509B iPTF14atg SN 1940B SN 1979C SN 2005ap SN 2006X SN 2020oi Category

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Adapted from the Wikipedia article [12 Comae Berenices](https://en.wikipedia.org/wiki/12_Comae_Berenices) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/12_Comae_Berenices?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.