Rho1 Cephei
Star in the constellation Cepheus
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Rho1 Cephei is a double star located in the northern constellation of Cepheus. Its name is a Bayer designation that is Latinized from ρ1 Cephei, and abbreviated Rho1 Cep or ρ1 Cep. As of 2014, the pair had an angular separation of 0.29 arc seconds along a position angle of 211.1°. This corresponds to a projected separation of 18.1 AU.[3] Rho1 Cephei is faintly visible to the naked eye with an apparent visual magnitude of 5.84,[2] and it forms an optical pair with the brighter star Rho2 Cephei. Based upon an annual parallax shift of 16.26 mas as seen from the Earth,[1] Rho1 Cephei is located approximately 201 light-years (62 pc) from the Sun.
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Cepheus |
| Right ascension | 22h 26m 42.434s[1] |
| Declination | +78° 47′ 09.144″[1] |
| Apparent magnitude (V) | 5.84[2] |
| Characteristics | |
| Spectral type | A2m[3] |
| B−V color index | −0.16[2] |
| Astrometry | |
| Proper motion (μ) | RA: −18.440 mas/yr[1] Dec.: −48.707 mas/yr[1] |
| Parallax (π) | 16.2606±0.0414 mas[1] |
| Distance | 200.6 ± 0.5 ly (61.5 ± 0.2 pc) |
| Details | |
| ρ1 Cep A | |
| Mass | 2.00 M☉[3] 1.82±0.04 M☉ |
| Radius | 1.870±0.038[1] R☉ |
| Luminosity | 13.89±0.08[1] L☉ |
| Surface gravity (log g) | 3.8997+0.003 −0.005 cgs |
| Temperature | 7,600+9 −7[1] K |
| Rotational velocity (v sin i) | 81[4] km/s |
| Age | 320 Myr[3] 683±165[1] Myr |
| ρ1 Cep B | |
| Mass | 0.51[3] M☉ |
| Other designations | |
| ρ1 Cep, 28 Cep, BD+78°796, HD 213403, HIP 110787, HR 8578, SAO 10375, WDS J22267+7847AB[5] | |
| Database references | |
| SIMBAD | data |
The primary component is a chemically peculiar Am star with a stellar classification of A2m.[3] It has twice the mass of the Sun and is around 320 million years old.[3] The smaller companion may be the source of the X-ray emission from this location, as stars similar to the primary component do not generally produce detectable levels of X-rays.[6]