Iota Octantis

Iota Octantis, Latinized from ι Octantis, is a double star^[10] in the southern circumpolar constellation Octans. The two components are separated by less than an arc-second, so cannot be resolved without a telescope, but their combined apparent magnitude of 5.45^[6] makes Iota Octantis faintly visible to the naked eye in dark skies. The system is located at a distance of 350 light years^[5] based on its annual parallax shift, and is drifting away at a rate of 53.4 km/s.^[4]

ι Octantis

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Octans
A
Right ascension	12h 54m 58.80097s[1]
Declination	−85° 07′ 24.1092″[1]
Apparent magnitude (V)	5.83[1]
B
Right ascension	12h 54m 58.33659s[1]
Declination	−85° 07′ 24.4647″[1]
Apparent magnitude (V)	6.75[1]
Characteristics
Spectral type	K0III + K0[2]
U−B color index	+0.79[3]
B−V color index	+1.02[3]
Astrometry
Radial velocity (Rv)	53.4±0.7[4] km/s
Proper motion (μ)	RA: +67.20[5] mas/yr Dec.: +24.76[5] mas/yr
Parallax (π)	9.27±0.46 mas[5]
Distance	350 ± 20 ly (108 ± 5 pc)
Absolute magnitude (MV)	+0.29[6]
Details[7]
Mass	2.49+1.48 −1.31 M☉
Luminosity	81±9 L☉
Temperature	4,890±110 K
Metallicity [Fe/H]	−0.3 dex
Rotational velocity (v sin i)	1.9±1.3[8] km/s
Age	725[9] Myr
Other designations
ι Octantis, 16 G. Octantis, CPD−84°407, GC 17460, HD 111482, HIP 63031, HR 4870, SAO 258654, WDS J12550-8507AB
Database references
SIMBAD	data

Iota Octantis A has a classification of K0 III, which indicates that it is an evolved K-type star that exhausted hydrogen at its core and left the main sequence. Iota Octantis B also has a spectral type of K0. At present Iota Octantis A has 2.49 times the mass of the Sun^[7] and radiates at 81 times the luminosity of the Sun^[7] from its enlarged photosphere at an effective temperature of 4,890 K,^[7] which gives it an orangish-yellow hue. Iota Octantis is metal deficient^[7] and spins slowly with a projected rotational velocity of 1.9 km/s.^[8]

Eggleton et al. states that both stars have similar spectral types,^[10] but there is a faint tenth magnitude companion with a classification of F8 located 60.1″ away,^[11] which is unrelated to the two.