Phi Octantis

Phi Octantis, Latinized from φ Octantis, is a solitary star^[14] located in the southern circumpolar constellation Octans. It has an apparent magnitude of 5.46,^[2] making it faintly visible to the naked eye if viewed under ideal conditions. The object is located relatively close at a distance of 194 light years based on Gaia DR3 parallax measurements,^[1] but it is receding with a heliocentric radial velocity of approximately 5 km/s.^[5] At its current distance, Phi Octantis' brightness is diminished by 0.26 magnitudes due to interstellar extinction and it has an absolute magnitude of +1.60.^[6]

φ Octantis

Location of Phi Oct on the map (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Octans
Right ascension	18h 23m 36.44874s[1]
Declination	−75° 02′ 39.3975″[1]
Apparent magnitude (V)	5.46±0.01[2]
Characteristics
Spectral type	A0 V[3]
U−B color index	+0.04[4]
B−V color index	+0.02[4]
Astrometry
Radial velocity (Rv)	5.0±4.2[5] km/s
Proper motion (μ)	RA: +4.621 mas/yr[1] Dec.: +19.730 mas/yr[1]
Parallax (π)	16.8258±0.0636 mas[1]
Distance	193.8 ± 0.7 ly (59.4 ± 0.2 pc)
Absolute magnitude (MV)	+1.60[6]
Details
Mass	2.86[7] M☉
Radius	1.74±0.08[8] R☉
Luminosity	21.1±0.1[1] L☉
Surface gravity (log g)	4.48±0.14[7] cgs
Temperature	9,352±122[9] K
Metallicity [Fe/H]	−0.22[10] dex
Rotational velocity (v sin i)	295[11] km/s
Age	7[7] Myr
Other designations
φ Oct, 33 G. Octantis[12], CPD−75°1417, GC 24999, HD 167468, HIP 90133, HR 6829, SAO 257584[13]
Database references
SIMBAD	data

Phi Octantis has a stellar classification of A0 V,^[3] indicating that it is an ordinary A-type main-sequence star that is generating energy via hydrogen fusion at is core. At present it has 2.7 times the mass of the Sun^[7] and 1.74 times the radius of the Sun.^[8] It radiates at 21.1 times the luminosity of the Sun^[1] from its photosphere at an effective temperature of 9,352 K,^[9] giving it a white hue when viewed in the night sky. Phi Octantis is a relatively young star with an age of only 7 million years^[7] and it spins rapidly with a projected rotational velocity of 295 km/s.^[11] It has a metallicity only 60% of the Sun's at [Fe/H] = −0.22.