Upsilon Octantis

Upsilon Octantis (Upsilon Oct), Latinized from υ Octantis, is a solitary star^[11] in the southern circumpolar constellation Octans. It is faintly visible to the naked eye with an apparent magnitude of 5.75^[2] and is located 343 light years away from the Solar System.^[1] However, it is receding with a heliocentric radial velocity of 19 km/s.^[5]

υ Octantis

Location of υ Octantis (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Octans
Right ascension	22h 31m 37.5152s[1]
Declination	−85° 58′ 02.110″[1]
Apparent magnitude (V)	5.75±0.01[2]
Characteristics
Spectral type	K0 III[3]
U−B color index	+0.88[4]
B−V color index	+1.02[4]
Astrometry
Radial velocity (Rv)	19±7.8[5] km/s
Proper motion (μ)	RA: −37.556 mas/yr[1] Dec.: +61.431 mas/yr[1]
Parallax (π)	9.5042±0.0351 mas[1]
Distance	343 ± 1 ly (105.2 ± 0.4 pc)
Absolute magnitude (MV)	+0.77[6]
Details[7]
Mass	2.12±0.07 M☉
Radius	10.3±0.2 R☉
Luminosity	56±1.1 L☉
Surface gravity (log g)	2.7±0.1 cgs
Temperature	4,910±42 K
Metallicity [Fe/H]	0.00±0.03 dex
Rotational velocity (v sin i)	1.5±1.3[8] km/s
Other designations
υ Oct, 71 G. Octantis[9], CPD−86°406, FK5 1670, GC 31327, HD 211539, HIP 111196, HR 8505, SAO 258932[10]
Database references
SIMBAD	data

Upsilon Oct has a stellar classification of K0 III,^[3] indicating that it is a red giant. At present it has 2.12 times the mass of the Sun but has expanded to 10.3 times its girth.^[7] It shines with a luminosity of 56 L_☉ from its enlarged photosphere at an effective temperature of 4,910 K,^[7] giving a yellowish orange hue when viewed at night. Upsilon Oct has a solar metallicity, with an iron abundance equivalent to the Sun's.^[7] It spins leisurely with a poorly-constrained projected rotational velocity of 1.5 km/s.^[8]