Gamma3 Octantis
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Octans |
| Right ascension | 00h 10m 02.17249s |
| Declination | −82° 13′ 26.5695″ |
| Apparent magnitude (V) | 5.28±0.01 |
| Characteristics | |
| Evolutionary stage | Horizontal branch |
| Spectral type | K1/2 III |
| U−B color index | +0.92 |
| B−V color index | +1.05 |
| Astrometry | |
| Radial velocity (Rv) | 15±2.8 km/s |
| Proper motion (μ) | RA: −22.050 mas/yr Dec.: −20.218 mas/yr |
| Parallax (π) | 12.3535±0.0517 mas |
| Distance | 264 ± 1 ly (80.9 ± 0.3 pc) |
| Absolute magnitude (MV) | +0.83 |
| Details | |
| Mass | 2.23±0.09 M☉ |
| Radius | 9.94±0.24 R☉ |
| Luminosity | 50.5±1.2 L☉ |
| Surface gravity (log g) | 2.78±0.15 cgs |
| Temperature | 4,879±51 K |
| Metallicity [Fe/H] | +0.19±0.04 dex |
| Rotational velocity (v sin i) | <1 km/s |
| Other designations | |
| γ3 Octantis, 1 G. Octantis, CPD−82°4, FK5 3971, GC 173, HD 636, HIP 814, HR 30, SAO 258215 | |
| Database references | |
| SIMBAD | data |
Gamma3 Octantis, Latinized from γ3 Octantis, is a solitary star located in the southern circumpolar constellation Octans. It is faintly visible to the naked eye as an orange-hued star with an apparent magnitude of 5.28. The object is located relatively close at a distance of 264 light years but is receding with a heliocentric radial velocity of 15 km/s. At its current distance, Gamma3 Octantis' brightness is diminished by two tenths of a magnitude due to interstellar dust and Eggen (1993) lists it as a member of the old disk population. It has an absolute magnitude of +0.83.
Gamma3 Octantis has a stellar classification of K1/2 III, indicating that it is an evolved K-type star with the characteristics of a K1 and K2 giant star. It is a red clump star that is currently on the horizontal branch, fusing helium at its core. At present it has 2.23 times the mass of the Sun but has expanded to almost 10 times its girth. It radiates 50.5 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,879 K, which gives it a yellowish-orange glow. Gamma3 Octantis is metal enriched with an iron abundance 1.55 times that of the Sun and common for giant stars, spins slowly with a projected rotational velocity less than 1 km/s.