Kappa Cephei
Star in the constellation Cepheus
From Wikipedia, the free encyclopedia
Kappa Cephei is a binary star[10] system in the northern circumpolar constellation of Cepheus. Its name is a Bayer designation that is Latinized from κ Cephei, and abbreviated Kappa Cep or κ Cep. It is visible to the naked eye as a faint, blue white-hued point of light with an apparent visual magnitude is 4.39.[11] The system is located approximately 323 light-years (99 pc) distant from the Earth, based on parallax measurements. It is drifting closer to the Sun with a line of sight velocity component of −23 km/s.[5]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cepheus[1] |
| Right ascension | 20h 08m 53.34492s[2] |
| Declination | +77° 42′ 41.0909″[2] |
| Apparent magnitude (V) | 4.39[3] |
| Characteristics | |
| Spectral type | B9III + A7V[4] |
| U−B color index | −0.11[3] |
| B−V color index | −0.05[3] |
| Astrometry | |
| Absolute magnitude (MV) | −0.54[1] |
| Kap Cep A | |
| Radial velocity (Rv) | −22.8±0.9[5] km/s |
| Proper motion (μ) | RA: +12.044 mas/yr[2] Dec.: +26.199 mas/yr[2] |
| Parallax (π) | 10.0861±0.2468 mas[2] |
| Distance | 323 ± 8 ly (99 ± 2 pc) |
| Kap Cep B | |
| Radial velocity (Rv) | −15.3±5[5] km/s |
| Proper motion (μ) | RA: +10.725±0.047[6] mas/yr Dec.: +25.543±0.056[6] mas/yr |
| Parallax (π) | 9.9981±0.0290 mas[6] |
| Distance | 326.2 ± 0.9 ly (100.0 ± 0.3 pc) |
| Details | |
| Kap Cep A | |
| Mass | 3.02±0.5[7] M☉ |
| Radius | 4.45±0.22[8] R☉ |
| Luminosity | 191[1] L☉ |
| Surface gravity (log g) | 3.66±0.03[8] cgs |
| Temperature | 10,174±55[8] K |
| Metallicity [Fe/H] | −0.05[1] dex |
| Age | 302+77 −72[7] Myr |
| Kap Cep B | |
| Radius | 1.32[6] R☉ |
| Luminosity | 4.05[6] L☉ |
| Temperature | 7,119[6] K |
| Other designations | |
| κ Cep, 1 Cephei, BD+77°764, HD 192907, HIP 99255, HR 7750, SAO 9665, GSC 04589-03106[9] | |
| Database references | |
| SIMBAD | data |
| B | |
| C | |
The two gravitationally-bound members of this system had an angular separation of 7.3″ along a position angle of 120°, as of 2015.[11] The primary, designated component A, has a stellar classification of B9III,[4] presenting as a blue giant. The magnitude 8.34 secondary, component B, is an A-type main-sequence star of class A7V.[4] A third star of 10th magnitude, BD+77 763, is listed as component C in the Washington Double Star Catalog although it is a background object unrelated to the other two. [11]