Omicron Andromedae
 Location of ο Andromedae (far right) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Andromeda |
| Right ascension | 23h 01m 55.26459s |
| Declination | +42° 19′ 33.5334″ |
| Apparent magnitude (V) | 3.62(3.55 - 3.78) |
| Characteristics | |
| Spectral type | B6III + A2 |
| 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 ± 0.53mas |
| Distance | approx. 690 ly (approx. 210 pc) |
| Absolute magnitude (MV) | −2.6 |
| Orbit | |
| Primary | A |
| Companion | B |
| Period (P) | 159.7 years |
| Semi-major axis (a) | 0.322" (68.4 AU) |
| Eccentricity (e) | 0.55 |
| Inclination (i) | 114.7° |
| Orbit | |
| Primary | Aa |
| Companion | Ab |
| Period (P) | 8.3 years |
| Semi-major axis (a) | 0.040" (8.5 AU) |
| Eccentricity (e) | 0.55 |
| Inclination (i) | 179.9° |
| Orbit | |
| Primary | Aa1 |
| Companion | Aa2 |
| Period (P) | 33.01 days |
| Eccentricity (e) | 0.24 |
| Details | |
| ο And Aa | |
| Mass | 3.6 + 2.9 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 | 2.4 M☉ |
| ο And B | |
| Mass | 3.6 M☉ |
| Age | 50.1 ± 6.8 Myr |
| Other designations | |
| ο And A: HD 217675 | |
| ο And B: HD 217676 | |
| Database references | |
| SIMBAD | data |
Omicron Andromedae (ο And, ο Andromedae) is a star system in the constellation Andromeda. It is approximately 692 light years from Earth.
Omicron Andromedae is a binary star, whose two components are both spectroscopic binaries themselves, making a four-star system. The system as a whole is classified as a blue-white B-type giant, with a mean combined apparent magnitude of +3.62.
The separation of the two brightest components, ο Andromedae A and ο Andromedae B, is 0.34 arcseconds. They have an orbital period of 68.6 years. A is separated from its spectroscopic companion by 0.05 arcseconds. A is a Gamma Cassiopeiae type variable star and the system's brightness varies from magnitude +3.58 to +3.78. This, in turn, has made determination the orbital period of A's spectroscopic binary difficult. B's spectroscopic companion was discovered in 1989, and that binary has a period of 33.01 years.
This star system has a peculiar velocity of 34.5 ± 5.9 km/s.
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