31 Pegasi
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Pegasus |
| Right ascension | 22h 21m 31.07511s |
| Declination | 12° 12′ 18.6628″ |
| Apparent magnitude (V) | 4.99 |
| Characteristics | |
| Spectral type | B2IV-Ve |
| U−B color index | -0.81 |
| B−V color index | -0.10 |
| Variable type | γ Cas |
| Astrometry | |
| Radial velocity (Rv) | −5.30 km/s |
| Proper motion (μ) | RA: +6.32 mas/yr Dec.: +4.80 mas/yr |
| Parallax (π) | 2.01±0.28 mas |
| Distance | approx. 1,600 ly (approx. 500 pc) |
| Absolute magnitude (MV) | −3.61 |
| Details | |
| Mass | 12.5±0.7 M☉ |
| Luminosity (bolometric) | 27,925+4,360 −3,770 L☉ |
| Surface gravity (log g) | 3.71±0.15 cgs |
| Temperature | 23,890±740 K |
| Rotational velocity (v sin i) | 98±8 km/s |
| Age | 15.4±1.3 Myr |
| Other designations | |
| 31 Peg, IN Peg, BD+11°4784, FK5 843, GC 31255, HD 212076, HIP 110386, HR 8520, SAO 107854 | |
| Database references | |
| SIMBAD | data |
31 Pegasi is a single star in the northern constellation of Pegasus. It is visible to the naked eye as a dim, blue-white hued point of light with a baseline apparent visual magnitude of 4.99. It is located approximately 1,600 light years away from the Sun based on parallax, but is drifting closer with a radial velocity of −5.3 km/s.
This is a massive Be star with a stellar classification of B2IV-V. It is a γ Cas variable; a type of shell star with a circumstellar disc of gas surrounding the star at the equator, and ranges from 5.05 up to 4.85 in visual magnitude. It is spinning with a projected rotational velocity of 98 km/s, with the pole being inclined by an estimated angle of 26°±9° to the line of sight from the Earth. The star is 15.4 million years old with 12.5 times the mass of the Sun. It is radiating around 28,000 times the luminosity of the Sun from its photosphere at an effective temperature of 23,890 K.