24 Cephei
Star in the constellation Cepheus
From Wikipedia, the free encyclopedia
24 Cephei is a single,[10] yellow-hued star in the northern circumpolar constellation of Cepheus. With an apparent visual magnitude of 4.79,[2] it is faintly visible to the naked eye. The distance to this star, based upon an annual parallax shift of 8.28 mas,[1] is around 394 light years. It is moving closer with a heliocentric radial velocity of −17 km/s.[4]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cepheus |
| Right ascension | 22h 09m 48.43066s[1] |
| Declination | +72° 20′ 28.3397″[1] |
| Apparent magnitude (V) | 4.79[2] |
| Characteristics | |
| Evolutionary stage | red giant branch[1] |
| Spectral type | G7 II-III[3] |
| B−V color index | 0.898[4] |
| Astrometry | |
| Radial velocity (Rv) | −16.58[4] km/s |
| Proper motion (μ) | RA: +33.041[1] mas/yr Dec.: +2.809[1] mas/yr |
| Parallax (π) | 8.2802±0.0916 mas[1] |
| Distance | 394 ± 4 ly (121 ± 1 pc) |
| Absolute magnitude (MV) | −0.519[4] |
| Details | |
| Mass | 3.50[5] M☉ |
| Radius | 16.8[6] R☉ |
| Luminosity | 209[5] L☉ |
| Surface gravity (log g) | 2.31±0.33[7] cgs |
| Temperature | 5,023±54[7] K |
| Metallicity [Fe/H] | −0.16±0.11[7] dex |
| Rotational velocity (v sin i) | 6.5[8] km/s |
| Age | 234[5] Myr |
| Other designations | |
| 24 Cep, BD+71°1111, FK5 837, HD 210807, HIP 109400, HR 8468, SAO 10265[9] | |
| Database references | |
| SIMBAD | data |
Keenan and McNeil (1989) listed a stellar classification of G7 II-III[3] for 24 Cep, matching the spectrum of an evolved G-type star with blended features of a bright giant and a giant star. Older sources list a class of G8 III,[11] which would suggest an ordinary giant star. At the age of 234 million years,[5] it has an estimated 3.5 times the mass of the Sun[5] and has expanded to about 17 times the Sun's radius.[6] The star is radiating 199 times the Sun's luminosity[2] from its enlarged photosphere at an effective temperature of 5,023 K.[7] These coordinates are a source of X-ray emission.[12]