Omicron Cephei
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) |
|
|---|---|
| Constellation | Cepheus |
| ο Cep A | |
| Right ascension | 23h 18m 37.493s |
| Declination | +68° -6′ 41.20″ |
| Apparent magnitude (V) | 4.86 |
| ο Cep B | |
| Right ascension | 23h 18m 37.115s |
| Declination | +68° 06′ 38.65″ |
| Apparent magnitude (V) | 7.13 |
| Characteristics | |
| U−B color index | +0.49 |
| B−V color index | +0.84 |
| R−I color index | +0.45 |
| ο Cep A | |
| Spectral type | G8III |
| ο Cep B | |
| Spectral type | F6V |
| Astrometry | |
| ο Cep A | |
| Proper motion (μ) |
RA: 54.88 mas/yr Dec.: 10.91 mas/yr |
| Parallax (π) | 15.48 ± 0.55mas |
| Distance | 211 ± 7 ly (65 ± 2 pc) |
| Absolute magnitude (MV) | 0.8 |
| ο Cep B | |
| Proper motion (μ) |
RA: 45.70 mas/yr Dec.: 13.19 mas/yr |
| Absolute magnitude (MV) | 3.1 |
| Orbit | |
| Period (P) | 1505 ± 40 y |
| Semi-major axis (a) | 3.13 ± 0.12″ |
| Eccentricity (e) | 0.439 ± 0.020 |
| Inclination (i) | 16.0 ± 4.0° |
| Longitude of the node (Ω) | 4.5 ± 4.5° |
| Periastron epoch (T) | B1692 ± 20 |
|
Argument of periastron (ω) (secondary) |
93.0 ± 20.0° |
| Details | |
| ο Cep A | |
| Mass | 2.35 ± 0.15 M☉ |
| ο Cep B | |
| Mass | 1.29 M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) |
|
|---|---|
| Constellation | Cepheus |
| Right ascension | 23h 18m 37.5s |
| Declination | +68° 07′ 26″ |
| Apparent magnitude (V) | 12.8 |
| Position (relative to A) | |
| Epoch of observation | 1912 |
| Angular distance | 45.6″ |
| Position angle | 4° |
| Other designations | |
| Database references | |
| SIMBAD | data |
Omicron Cephei (Omicron Cep, ο Cephei, ο Cep) is a binary star in the constellation of Cepheus. It consists of a less massive F-type main sequence star in orbit with a more massive G-type giant star. The overall apparent visual magnitude of the system is 4.75.
The pair was first determined to be binary by F. G. W. Struve in 1832. Since then, the secondary has been seen to revolve approximately 45 degrees around the primary. A number of orbits have been computed, the most recent giving a period of approximately 1500 years.
There is a visual companion, CCDM J23186+6807C, to the binary star. It has an approximate apparent visual magnitude of 12.8 and is located approximately 45 arcseconds away from it.
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