31 Comae Berenices
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. It is currently in the Hertzsprung gap and its outer envelope has just begun convection. In 1989 it was given as a spectral standard for the class G0IIIp.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Coma Berenices |
| Right ascension | 12h 51m 41.91900s |
| Declination | +27° 32′ 26.5683″ |
| Apparent magnitude (V) | 4.87 - 4.97 |
| Characteristics | |
| Evolutionary stage | Hertzsprung gap |
| Spectral type | G0III |
| Variable type | FK Com |
| Astrometry | |
| Proper motion (μ) | RA: −10.990 mas/yr Dec.: −8.313 mas/yr |
| Parallax (π) | 11.4933 ± 0.1828 mas |
| Distance | 284 ± 5 ly (87 ± 1 pc) |
| Details | |
| 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.
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).