81 Ceti
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cetus |
| Right ascension | 02h 37m 41.80208s |
| Declination | −03° 23′ 46.2259″ |
| Apparent magnitude (V) | 5.65 |
| Characteristics | |
| Evolutionary stage | red clump |
| Spectral type | K0III or G5III |
| B−V color index | 1.021±0.001 |
| Astrometry | |
| Radial velocity (Rv) | +9.14±0.12 km/s |
| Proper motion (μ) | RA: 41.765 mas/yr Dec.: −43.379 mas/yr |
| Parallax (π) | 9.5199±0.0756 mas |
| Distance | 343 ± 3 ly (105.0 ± 0.8 pc) |
| Absolute magnitude (MV) | 0.82 |
| Details | |
| Mass | 1.6±0.2 M☉ |
| Radius | 11.1±0.3 R☉ |
| Luminosity | 60.0±0.8 L☉ |
| Surface gravity (log g) | 2.5±0.1 cgs |
| Temperature | 4,825±41 K |
| Metallicity [Fe/H] | 0.00±0.04 dex |
| Rotational velocity (v sin i) | 1.20±0.47 km/s |
| Age | 2.5±0.9 Gyr |
| Other designations | |
| 81 Cet, BD−04°436, GC 3158, HD 16400, HIP 12247, HR 771, SAO 130026 | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
81 Ceti is a star located approximately 343 light-years away from the Sun in the equatorial constellation of Cetus. 81 Ceti is the Flamsteed designation for this object. It is visible to the naked eye as a dim, yellow-hued point of light with an apparent visual magnitude of 5.65. The star is drifting further away from the Earth with a heliocentric radial velocity of +9 km/s.
This is an aging K-type giant star with a stellar classification of K0III, having exhausted the supply of hydrogen at its core and expanded to 11 times the Sun's radius. It is a red clump giant, which indicates it is on the horizontal branch and is generating energy from core helium fusion. The star is now 2.5 billion years old with 1.6 times the mass of the Sun. It is radiating 60 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,825 K.