  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Octans[1] |
| Right ascension | 00h 01m 35.70158s[2] |
| Declination | −77° 03′ 56.6092″[2] |
| Apparent magnitude (V) | 4.78[1] |
| Characteristics | |
| Evolutionary stage | red clump[3] |
| Spectral type | K3III[4] |
| U−Bcolor index | +1.41[5] |
| B−Vcolor index | +1.27[5] |
| Astrometry | |
| Radial velocity (Rv) | +22.48±0.17[6] km/s |
| Proper motion (μ) | RA: −57.30[2]mas/yr Dec.: −177.06[2]mas/yr |
| Parallax (π) | 15.02±0.18 mas[2] |
| Distance | 217 ± 3 ly (66.6 ± 0.8 pc) |
| Absolute magnitude (MV) | 0.66[1] |
| Details | |
| Mass | 1.20[7] M☉ |
| Radius | 15.84+0.42 −1.02[6] R☉ |
| Luminosity | 79.2±1.5[6] L☉ |
| Surface gravity (log g) | 2.16[7] cgs |
| Temperature | 4,325+147 −55[6] K |
| Rotational velocity (v sin i) | < 1.0[8] km/s |
| Other designations | |
| θ Oct,CPD−77°1596,FK5 904,GC 33321,HD 224889,HIP 122,HR 9084,SAO 258207[9] | |
| Database references | |
| SIMBAD | data |
θ Octantis,Latinized asTheta Octantis, is a single[10]star in the southerncircumpolar constellation ofOctans, near the constellation border withHydrus. It is visible to the naked eye as a faint, orange-hued star with anapparent visual magnitude of 4.78.[1] The star is located approximately 217 light years from the Sun based onparallax,[2] and is drifting further away with aradial velocity of +22.5 km/s.[6]
This is an aginggiant star with astellar classification of K3III,[4] having exhausted the supply of hydrogen at itscore then cooled and expanded. It has been catalogued as ared clump giant,[3] which would indicate it is on thehorizontal branch and is undergoing corehelium fusion. At present it has 16[6] times theradius of the Sun. This star has 1.20[7] times themass of the Sun and is radiating 79[6] times theSun's luminosity from its enlargedphotosphere at aneffective temperature of 4,325 K.[6]
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