Zeta Cephei
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cepheus |
| Right ascension | 22h 10m 51.277s |
| Declination | +58° 12′ 04.54″ |
| Apparent magnitude (V) | 3.35 |
| Characteristics | |
| Evolutionary stage | Red supergiant |
| Spectral type | K1.5 Ib |
| B−V color index | +1.55 |
| Astrometry | |
| Proper motion (μ) | RA: 13.359±0.148 mas/yr Dec.: 5.275±0.183 mas/yr |
| Parallax (π) | 3.2972±0.1456 mas |
| Distance | 992.7+51.2 −46 ly (304.5+15.7 −14.1 pc) |
| Absolute magnitude (MV) | −4.7 |
| Details | |
| Mass | 10.1±0.1 M☉ |
| Radius | 172.7+7.5 −8.3 R☉ |
| Luminosity | 10,024±1,052 L☉ |
| Surface gravity (log g) | 0.75 cgs |
| Temperature | 4,393±58 K |
| Metallicity [Fe/H] | +0.04 dex |
| Rotational velocity (v sin i) | 10.64 km/s |
| Other designations | |
| 21 Cephei, BD+57°2475, FK5 836, HD 210745, HIP 109492, HR 8465, SAO 34137, Gaia DR2 2199493438511811712, Gaia DR3 2199493438511811712 | |
| Database references | |
| SIMBAD | data |
Zeta Cephei is a red supergiant star in the northern constellation of Cepheus. Its name is a Bayer designation that is Latinized from ζ Cephei, and abbreviated Zeta Cep or ζ Cep. With an apparent visual magnitude of 3.35, it is a third-magnitude star that is visible to the naked eye. Based on parallax measurements, it is located about 1000 light-years away from the Earth. Zeta Cephei marks the left shoulder of Cepheus, a mythical King of Aethiopia. It is one of the fundamental stars of the MK spectral sequence, defined as type K1.5 Ib.