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Location of φ Andromedae (upper left). |
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| Observation data Epoch J2000 Equinox J2000 |
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|---|---|
| Constellation | Andromeda |
| Right ascension | 01h 09m 30.13s[1] |
| Declination | +47° 14′ 30.5″[1] |
| Apparent magnitude (V) | 4.252 |
| Characteristics | |
| Spectral type | B7V |
| U−B color index | -0.34 |
| B−V color index | -0.07 |
| R−I color index | -0.05 |
| Variable type | Emission-line Star |
| Astrometry | |
| Radial velocity (Rv) | -0.1 km/s |
| Proper motion (μ) | RA: 4.05 ± 0.52[1] mas/yr Dec.: -12.43 ± 0.38[1] mas/yr |
| Parallax (π) | 4.55 ± 0.60[1] mas |
| Distance | approx. 720 ly (approx. 220 pc) |
| Absolute magnitude (MV) | 4.197 |
| Details | |
| Mass | 18 M☉ |
| Radius | 7 R☉ |
| Luminosity | 20.000 L☉ |
| Temperature | 10.000–30.000 K |
| Rotational velocity (v sin i) | 71 Km/s km/s |
| Orbit | |
| Companion | φ Andromedae B |
| Period (P) | 371.6 yr |
| Semimajor axis (a) | 0.447" |
| Eccentricity (e) | 0.21 |
| Inclination (i) | 131° |
| Longitude of the node (Ω) | 148.2° |
| Periastron epoch (T) | 1889.9 |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Database references | |
| SIMBAD | data |
Phi Andromedae (φ Andromedae, φ And) is a binary star system near the border of the constellation of Andromeda, approximately 720 light years from the Earth.[1] With χ And it forms the Chinese asterism 軍南門 (Keun Nan Mun, Mandarin jūnnánmén), "the South Gate of the Camp".[2][3]
The primary component, φ And A, is a blue-white B-type subgiant with an apparent magnitude of 4.6m. The companion star, φ And B, is a blue-white B-type main sequence dwarf with an apparent magnitude of 5.6m. The two stars are separated by 0.64 arcseconds and have an orbital period of 371.6 years. The combined brightness of the system is 4.26m.
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