72 Pegasi
Binary star system in the constellation Pegasus From Wikipedia, the free encyclopedia
Binary star system in the constellation Pegasus From Wikipedia, the free encyclopedia
72 Pegasi is a binary star system in the northern constellation of Pegasus. It is visible to the naked eye as a faint, orange-hued point of light with a combined apparent visual magnitude of 4.97.[2] The system is located approximately 550 light years away from the Sun, based on parallax,[1] but is drifting closer with a radial velocity of −25 km/s.[6]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Pegasus |
| Right ascension | 23h 33m 57.18791s[1] |
| Declination | 31° 19′ 31.0058″[1] |
| Apparent magnitude (V) | 4.97[2] |
| Characteristics | |
| Spectral type | K4IIIb[3] |
| U−B color index | +1.63[4] |
| B−V color index | +1.39[4] |
| Variable type | suspected[5] |
| Astrometry | |
| Radial velocity (Rv) | −24.71[6] km/s |
| Proper motion (μ) | RA: +50.81[1] mas/yr Dec.: −17.46[1] mas/yr |
| Parallax (π) | 5.94 ± 0.45 mas[1] |
| Distance | 550 ± 40 ly (170 ± 10 pc) |
| Absolute magnitude (MV) | −1.15[2] |
| Orbit[7] | |
| Period (P) | 492.30 ± 75.96 a (179,811 ± 27,745 d) |
| Semi-major axis (a) | 0.568 ± 0.065″ |
| Eccentricity (e) | 0.322 ± 0.047 |
| Inclination (i) | 21.7 ± 8.3° |
| Longitude of the node (Ω) | 56.2 ± 6.0° |
| Periastron epoch (T) | MJD 16818 ± 3658 |
| Argument of periastron (ω) (secondary) | 293 ± 15° |
| Details | |
| Mass | 2 / 2[7] M☉ |
| Luminosity | 554[2] L☉ |
| Surface gravity (log g) | 2.00[8] cgs |
| Temperature | 4,379[9] K |
| Metallicity [Fe/H] | +0.06[2] dex |
| Rotational velocity (v sin i) | 1.4[10] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is a visual binary with an orbital period of roughly 492 years and an eccentricity of 0.32. The two stars are relatively similar and are about twice the mass of the Sun each. The primary star, 72 Pegasi A, is an evolved K-type giant with a visual magnitude of 5.67. The companion, 72 Pegasi B, is another K-type giant with an apparent magnitude of 6.11, and a separation of about 0.568″ from the primary. 72 Pegasi B is thought to be a binary itself, with a brown dwarf companion in a 4.2-year period.[7]
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