Omega Octantis
Star in the constellation of Octans From Wikipedia, the free encyclopedia
Omega Octantis, (latinized from ω Octantis), is a solitary,[14] bluish-white hued star located in the southern circumpolar constellation Octans. It has an apparent magnitude of 5.87,[2] allowing it to be faintly seen with the naked eye. Based on the object's parallax measurements, it is estimated to be 328 light years distant.[1] However, it is drifting closer with a heliocentric radial velocity −7.6 km/s.[6]
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Octans |
| Right ascension | 15h 11m 08.79214s[1] |
| Declination | −84° 47′ 16.0295″[1] |
| Apparent magnitude (V) | 5.87±0.01[2] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | B9.5 V[4] |
| U−B color index | −0.13[5] |
| B−V color index | −0.06[5] |
| Astrometry | |
| Radial velocity (Rv) | −7.6±3[6] km/s |
| Proper motion (μ) | RA: +2.984 mas/yr[1] Dec.: −9.385 mas/yr[1] |
| Parallax (π) | 9.9406±0.0591 mas[1] |
| Distance | 328 ± 2 ly (100.6 ± 0.6 pc) |
| Absolute magnitude (MV) | +0.94[7] |
| Details | |
| Mass | 2.54[3] M☉ |
| Radius | 2.35±0.06[8] R☉ |
| Luminosity | 50.5+2.5 −2.4[3] L☉ |
| Surface gravity (log g) | 4.21[9] cgs |
| Temperature | 10,759±366[9] K |
| Metallicity [Fe/H] | 0.00[10] dex |
| Rotational velocity (v sin i) | 36[11] km/s |
| Age | 197[9] Myr |
| Other designations | |
| ω Oct, 23 G. Octantis[12], CPD−84°490, GC 20223, HD 131596, HIP 74296, HR 5557, SAO 258717[13] | |
| Database references | |
| SIMBAD | data |
Omega Octantis has a stellar classification of B9.5 V,[4] indicating that it is a main-sequence star between the B9 and A0 classes. Helmut A. Abt & Nidia I. Morrell gave a slightly updated class of B9.5 Vs,[15] which includes sharp (narrow) absorption lines in Omega Octantis' spectrum due to slow rotation. It has a mass 2.54 times that of the Sun[3] and is calculated to be 197 million years old,[9] having completed 40% of its main sequence lifetime.[3] It has a luminosity of 50.5 L☉,[3] which comes from a radius of 2.35 R☉ and an effective temperature of 10,759 K. In 2012, George A. Gontcharov calculated a solar metallicity for Omega Octantis,[10] and it is spinning modestly with a projected rotational velocity of 36 km/s.[11] The slow rotation is consistent with the spectral classification from Abt & Morell (1995).[15]
References
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