Phi Piscium

Phi Piscium, Latinized from φ Piscium, is a quadruple star^[6] system approximately 380 light years away in the constellation Pisces. It consists of Phi Piscium A, with a spectral type of K0III, and Phi Piscium B.^[5] Phi Piscium A possesses a surface temperature of 3,500 to 5,000 kelvins. Some suggest the only visible companion in the Phi Piscium B sub-system is a late F dwarf star, while others suggest it is a K0 star. The invisible component of the Phi Piscium B sub-system is proposed to have a spectral type of M2V.^[7] The star system has a period of about 20½ years and has a notably high eccentricity of 0.815.^[4]

Phi Piscium

Location of φ Piscium(circled)
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Pisces
Right ascension	01h 13m 44.94617s[1]
Declination	+24° 35′ 01.3249″[1]
Apparent magnitude (V)	4.676 (A)/9.11 (B)
Characteristics
φ Psc A
Spectral type	K0III[2]
B−V color index	+1.03
φ Psc B
Spectral type	K0
U−B color index	+0.25
B−V color index	+0.92
Astrometry
Radial velocity (Rv)	5.9 km/s
Proper motion (μ)	RA: 16.901[1] mas/yr Dec.: −21.415[1] mas/yr
Parallax (π)	8.1541±0.2028 mas[1]
Distance	400 ± 10 ly (123 ± 3 pc)
Absolute magnitude (MV)	−0.67[3]
Orbit[4]
Companion	φ Psc B
Period (P)	7473±3 d yr
Eccentricity (e)	0.815±0.005
Argument of periastron (ω) (secondary)	71.9±1.7°
Details
A
Radius	23.63+0.66 −1.36[1] R☉
Luminosity	249.6±7.1[1] L☉
Surface gravity (log g)	2.75[2] cgs
Temperature	4,720+142 −65[1] K
Metallicity [Fe/H]	−0.08[3] dex
Other designations
Phi Psc, φ Psc, 85 Piscium, BD+23°158, FK5 2082, GC 1474, HD 7318, HIP 5742, HR 360, SAO 74571, PPM 90580, CCDM J01137+2435A, WDS J01137+2435A[5]
Database references
SIMBAD	data

Naming

In Chinese, 奎宿 (Kuí Sù), meaning Legs (asterism), refers to an asterism consisting of refers to an asterism consisting of φ Piscium, η Andromedae, 65 Piscium, ζ Andromedae, ε Andromedae, δ Andromedae, π Andromedae, ν Andromedae, μ Andromedae, β Andromedae, σ Piscium, τ Piscium, 91 Piscium, υ Piscium, χ Piscium and ψ¹ Piscium. Consequently, φ Piscium itself is known as 奎宿十四 (Kuí Sù shí sì, English: the Fourteenth Star of Legs.)^[8]