Omega Octantis

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]

ω Octantis

Location of ω Oct (circled)
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]