31 Comae Berenices (31 Com) is a yellow giant star in the constellation Coma Berenices. Its apparent magnitude is about 4.9 and slightly variable. It is a rare FK Comae Berenices variable, a variable star that spins rapidly and has large starspots on its surface.[5] It is currently in the Hertzsprung gap and its outer envelope has just begun convection.[3] In 1989 it was given as a spectral standard for the class G0IIIp.[6]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Coma Berenices |
| Right ascension | 12h 51m 41.91900s[1] |
| Declination | +27° 32′ 26.5683″[1] |
| Apparent magnitude (V) | 4.87 - 4.97[2] |
| Characteristics | |
| Evolutionary stage | Hertzsprung gap[3] |
| Spectral type | G0III[4] |
| Variable type | FK Com[2] |
| Astrometry | |
| Proper motion (μ) | RA: −10.990[1] mas/yr Dec.: −8.313[1] mas/yr |
| Parallax (π) | 11.4933 ± 0.1828 mas[1] |
| Distance | 284 ± 5 ly (87 ± 1 pc) |
| Details[4] | |
| Radius | 8.9 R☉ |
| Luminosity | 74 L☉ |
| Surface gravity (log g) | 3.51 cgs |
| Temperature | 5,660 K |
| Metallicity [Fe/H] | −0.15 dex |
| Rotation | 6.8 d |
| Rotational velocity (v sin i) | 67 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
31 Com is the north galactic pole star, and occasionally goes by the informal name Polaris Galacticum Borealis, coined by Jim Kaler.[7]
In Chinese astronomy, 31 Comae Berenices is called 郎將, Pinyin: Lángjiāng, meaning Captain of the Bodyguards, because this star is marking itself and stand alone in Captain of the Bodyguards asterism, Supreme Palace enclosure mansion (see : Chinese constellation).[8]
References
edit- ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051.
- ^ a b Samus', N. N; Kazarovets, E. V; Durlevich, O. V; Kireeva, N. N; Pastukhova, E. N (2017), "General catalogue of variable stars: Version GCVS 5.1", Astronomy Reports, 61 (1): 80, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
- ^ a b Strassmeier, K. G.; et al. (September 2010), "Rotation and magnetic activity of the Hertzsprung-gap giant 31 Comae", Astronomy and Astrophysics, 520: 14, Bibcode:2010A&A...520A..52S, doi:10.1051/0004-6361/201015023, A52.
- ^ a b Aurière, M.; et al. (February 2015), "The magnetic fields at the surface of active single G-K giants", Astronomy & Astrophysics, 574: 30, arXiv:1411.6230, Bibcode:2015A&A...574A..90A, doi:10.1051/0004-6361/201424579, S2CID 118504829, A90.
- ^ a b "31 Com". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved September 13, 2018.
- ^ Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins Catalog of Revised MK Types for the Cooler Stars", The Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373
- ^ "Polaris Galacticum Borealis". Retrieved 2015-12-02.
- ^ Ian Ridpath's Startales - Coma Berenices the Berenice's Hair