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Theta Octantis
Star in the constellation Octans / From Wikipedia, the free encyclopedia
θ Octantis, Latinized as Theta Octantis, is a single[9] star in the southern circumpolar constellation of Octans, near the constellation border with Hydrus. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.78.[2] The star is located approximately 217 light years from the Sun based on parallax,[1] and is drifting further away with a radial velocity of +22.5 km/s.[5]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Octans |
Right ascension | 00h 01m 35.70158s[1] |
Declination | −77° 03′ 56.6092″[1] |
Apparent magnitude (V) | 4.78[2] |
Characteristics | |
Spectral type | K3III[3] |
U−B color index | +1.41[4] |
B−V color index | +1.27[4] |
Astrometry | |
Radial velocity (Rv) | +22.48±0.17[5] km/s |
Proper motion (μ) | RA: −57.30[1] mas/yr Dec.: −177.06[1] mas/yr |
Parallax (π) | 15.02 ± 0.18 mas[1] |
Distance | 217 ± 3 ly (66.6 ± 0.8 pc) |
Absolute magnitude (MV) | 0.66[2] |
Details | |
Mass | 1.20[6] M☉ |
Radius | 15.84+0.42 −1.02[5] R☉ |
Luminosity | 79.2±1.5[5] L☉ |
Surface gravity (log g) | 2.16[6] cgs |
Temperature | 4,325+147 −55[5] K |
Rotational velocity (v sin i) | < 1.0[7] km/s |
Other designations | |
Database references | |
SIMBAD | data |
This is an aging giant star with a stellar classification of K3III,[3] having exhausted the supply of hydrogen at its core then cooled and expanded. It has been catalogued as a red clump giant,[10] which would indicate it is on the horizontal branch and is undergoing core helium fusion. At present it has 16[5] times the radius of the Sun. This star has 1.20[6] times the mass of the Sun and is radiating 79[5] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,325 K.[5]