B Persei
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Perseus |
| Right ascension | 04h 18m 14.61690s |
| Declination | +50° 17′ 43.8058″ |
| Apparent magnitude (V) | 4.52 - 4.68 |
| Characteristics | |
| Spectral type | A1III |
| B−V color index | +0.04 |
| Variable type | Ellipsoidal |
| Astrometry | |
| Radial velocity (Rv) | 19.8±0.9 km/s |
| Proper motion (μ) | RA: 45.42±0.40 mas/yr Dec.: −56.72±0.32 mas/yr |
| Parallax (π) | 10.40±0.35 mas |
| Distance | 310 ± 10 ly (96 ± 3 pc) |
| Absolute magnitude (MV) | 0.3 |
| Orbit | |
| Primary | A or Aa |
| Companion | B or Ab |
| Period (P) | 1.52735997±0.00000036 days |
| Eccentricity (e) | 0.0 |
| Inclination (i) | 22±3 or 55±3° |
| Periastron epoch (T) | 2450001.0931±0.003 |
| Orbit | |
| Primary | AB |
| Companion | C or Ac |
| Period (P) | 703.06±0.07 days |
| Semi-major axis (a) | 26.22±0.06 mas |
| Eccentricity (e) | 0.185±0.003 |
| Inclination (i) | 90.5±0.1° |
| Longitude of the node (Ω) | 120.0±0.1° |
| Periastron epoch (T) | 2440080±3 |
| Argument of periastron (ω) (secondary) | 212±1° |
| Details | |
| A or Aa | |
| Mass | 2.25 M☉ |
| Radius | 3.2 R☉ |
| Luminosity | 59 L☉ |
| Temperature | 9,000 K |
| Rotational velocity (v sin i) | 81 km/s |
| B or Ab | |
| Mass | 0.56 M☉ |
| Radius | 0.25 R☉ |
| Luminosity | 4.5 - 5.9 L☉ |
| Temperature | 6,700 K |
| C or Ac | |
| Mass | 1.24 M☉ |
| Luminosity | 2 L☉ |
| Other designations | |
| BD+49°1150, GC 5174, HD 26961, HR 1324, HIP 20070, SAO 24531 | |
| Database references | |
| SIMBAD | data |
b Persei (also known as HD 26961) is a spectroscopic triple star in the constellation Perseus. Its apparent magnitude is 4.60, making it visible to the naked eye. It is about 320 light years away.
In addition to the primary, an A-type giant, there is a smaller and cooler companion in a 1.53 day orbit, probably an F-class star around absolute magnitude 3.0, and a more distant companion (star C or Ac) in an orbit calculated to be 702 days long. The close binary pair forms a rotating ellipsoidal variable with a 1.53 day period. Star C forms an Algol-type variable system with the close binary, showing both primary eclipses (when star C passes in front of the inner pair) and secondary eclipses (when the inner pair passes in front of star C). Timings of the eclipses show a 704.5-day period.