78 Pegasi
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Pegasus |
| Right ascension | 23h 43m 59.48560s |
| Declination | 29° 21′ 41.2342″ |
| Apparent magnitude (V) | 4.93 (5.07 / 8.10) |
| Characteristics | |
| Spectral type | K0III |
| U−B color index | +0.63 |
| B−V color index | +0.96 |
| Astrometry | |
| Radial velocity (Rv) | −8.33 km/s |
| Proper motion (μ) | RA: +71.10 mas/yr Dec.: -40.58 mas/yr |
| Parallax (π) | 14.54±0.56 mas |
| Distance | 224 ± 9 ly (69 ± 3 pc) |
| Absolute magnitude (MV) | 0.75 |
| Orbit | |
| Period (P) | 630.15 yr |
| Semi-major axis (a) | 1.614″ |
| Eccentricity (e) | 0.112 |
| Inclination (i) | 60.64° |
| Longitude of the node (Ω) | 172.55° |
| Periastron epoch (T) | B 2247.71 |
| Argument of periastron (ω) (secondary) | 241.27° |
| Details | |
| 78 Peg A | |
| Mass | 1.50 M☉ |
| Radius | 10 R☉ |
| Luminosity | 57.35 L☉ |
| Surface gravity (log g) | 2.62 cgs |
| Temperature | 4,898 K |
| Metallicity [Fe/H] | +0.01 dex |
| Rotational velocity (v sin i) | 1.1 km/s |
| Other designations | |
| 78 Peg, BD+28°4627, GC 32954, HD 222842, HIP 117073, HR 8997, SAO 91457, CCDM J23440+2922AB, WDS J23440+2922AB | |
| Database references | |
| SIMBAD | data |
78 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 an apparent visual magnitude of 4.93. The system is located approximately 224 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −8 km/s. The double-star nature of this system was discovered by A. G. Clark in 1862. The components of this system orbit each other over a 630-year period with an eccentricity of 0.11.
The primary member, designated component A, is a magnitude 5.07 giant star with a stellar classification of K0III, having exhausted the supply of hydrogen at its core and expanded to 10 times the Sun's radius. It is a red clump giant, which indicates it is on the horizontal branch and is generating energy through core helium fusion. It has 1.5 times the mass of the Sun and is radiating 57 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,898 K. The secondary companion, component B, is magnitude 8.10.