Omicron Andromedae
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 23h 01m 55.265s |
| Declination | +42° 19′ 33.66″ |
| Apparent magnitude (V) | 3.62 (3.55 - 3.78) |
| Characteristics | |
| Spectral type | B6III (B6IIIpe + A2p) |
| U−B color index | −0.53 |
| B−V color index | −0.09 |
| Variable type | γ Cas |
| Astrometry | |
| Radial velocity (Rv) | −14.0 km/s |
| Proper motion (μ) | RA: +22.99 mas/yr Dec.: +0.88 mas/yr |
| Parallax (π) | 4.75±0.53 mas |
| Distance | approx. 690 ly (approx. 210 pc) |
| Absolute magnitude (MV) | −2.6 |
| Orbit | |
| Primary | A |
| Companion | B |
| Period (P) | 118.0 yr |
| Semi-major axis (a) | 0.304″ |
| Eccentricity (e) | 0.340 |
| Inclination (i) | 107.4° |
| Orbit | |
| Primary | Aa |
| Companion | Ab |
| Period (P) | 5.6 yr |
| Semi-major axis (a) | 0.061″ |
| Eccentricity (e) | 0.22 |
| Inclination (i) | 152.0° |
| Orbit | |
| Primary | Ba |
| Companion | Bb |
| Period (P) | 33.01 days |
| Eccentricity (e) | 0.24 |
| Semi-amplitude (K1) (primary) | 54.8±0.8 km/s |
| Semi-amplitude (K2) (secondary) | 71.6±0.8 km/s |
| Details | |
| ο And Aa | |
| Mass | 9.85 M☉ |
| Radius | 6.6 R☉ |
| Luminosity | 1,380 L☉ |
| Temperature | 13,800 K |
| Rotational velocity (v sin i) | 240 km/s |
| ο And Ab | |
| Mass | 4.51 M☉ |
| ο And Ba | |
| Mass | 3.74 M☉ |
| ο And Bb | |
| Mass | 2.86 M☉ |
| Age | 50.1 ± 6.8 Myr |
| Other designations | |
| Alfarasalkamil, 1 And, AAVSO 2257+41, BD+41°4664, FK5 869, HIP 113726, HR 8762, SAO 52609, PPM 63726 | |
| ο And A: HD 217675 | |
| ο And B: HD 217676 | |
| Database references | |
| SIMBAD | data |
Omicron Andromedae, also named Alfarasalkamil, is a star system in the northern constellation Andromeda. Its Bayer designation is Latinized from ο Andromedae, and is abbreviated Omi And or ο And, respectively. Based on parallax measurements, it is located at a distance of approximately 690 light years from Earth. The system as a whole is classified as a blue-white B-type giant, with a typical combined apparent magnitude of +3.62. This is sufficiently bright that the star can be viewed with the naked eye on a dark night.