| |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Octans |
| Right ascension | 08h56m 40.97572s[1] |
| Declination | −85° 39′ 47.3476″[1] |
| Apparent magnitude (V) | 5.42±0.01[2] |
| Characteristics | |
| Spectral type | A8/9 IV[3] or F0 III[4] |
| U−B color index | +0.07[5] |
| B−V color index | +0.31[5] |
| Astrometry | |
| Radial velocity (Rv) | −3.6±2[6] km/s |
| Proper motion (μ) | RA: −117.699 mas/yr[1] Dec.: +33.964 mas/yr[1] |
| Parallax (π) | 20.9964 ± 0.0776 mas[1] |
| Distance | 155.3 ± 0.6 ly (47.6 ± 0.2 pc) |
| Absolute magnitude (MV) | +1.95[7] |
| Details | |
| Mass | 2.06±0.40[8] M☉ |
| Radius | 2.25±0.11[9] R☉ |
| Luminosity | 12.63±0.09[1] L☉ |
| Surface gravity (log g) | 4.04±0.28[8] cgs |
| Temperature | 7,063±325[10] K |
| Metallicity [Fe/H] | −0.36[11] dex |
| Rotational velocity (v sin i) | 115[12] km/s |
| Age | 1.25[13] Gyr |
| Other designations | |
ζ Oct, 9 G. Octantis[14], CPD−85°183, FK5 918, GC 12580, HD 79837, HIP 43908, HR 3678, SAO 258515[15] | |
| Database references | |
| SIMBAD | data |
Zeta Octantis, Latinized from ζ Octantis, is a solitary,[16] yellowish-white hued star located in the southern circumpolar constellation Octans. It has an apparent magnitude of 5.42,[2] making it faintly visible to the naked eye under ideal conditions. The star is located relatively close at a distance of only 156 light-years based on Gaia DR3 parallax measurements,[1] but is drifting closer with a radial velocityof−3.6 km/s.[6] At its current distance, Zeta Octantis' brightness is diminished by 0.25 magnitudes due to interstellar dust.[17]
This s an evolved A-type star with a stellar classification of A8/9 IV.[3] David S. Evans and colleagues, however, give it a classification of F0 III,[4] which suggests it is already an evolved giant star. It has double the Sun's mass,[8] and 2.25 times the Sun's radius.[9] It radiates around 13 times the luminosity of the Sun[1] from its photosphere at an effective temperatureof7,063 K.[10] Zeta Octantis is estimated to be 1.25 billion years olds based on stellar evolution models by Trevor J. David and Lynne A. Hillenbrand.[13] It has a low metallicity, having only 44% the abundance of heavy metals compared to the Sun.[11] Despite its advanced age, the object spins rapidly with a projected rotational velocityof115 km/s,[12] resulting in an oblate shape with a equatorial bulge 11% larger than the polar radius.[18]
