Phi Piscium

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Phi Piscium A/B[1]
Diagram showing star positions and boundaries of the Pisces constellation and its surroundings
Cercle rouge 100%.svg
Location of φ Piscium(circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Pisces
Right ascension 01h 13m 44.9471s
Declination +24° 35′ 01.367″
Apparent magnitude (V) 4.676 (A)/9.11 (B)
φ Psc A
Spectral type K0III
U−B color index +0.
B−V color index +1.03
φ Psc B
Spectral type K0
U−B color index +0.25
B−V color index +0.92
Radial velocity (Rv)5.9 km/s
Proper motion (μ) RA: 18.58 mas/yr
Dec.: -21.26 mas/yr
Parallax (π)8.64 ± 0.81 mas
Distance380 ± 40 ly
(120 ± 10 pc)
Absolute magnitude (MV)−0.67[2]
Orbit[3], p. 160
Companionφ Psc B
Period (P)7473 ± 3 days yr
Eccentricity (e)0.815 ± 0.005
Argument of periastron (ω)
71.9 ± 1.7°
Metallicity [Fe/H]−0.08[2] dex
Other designations
φ Piscium, 85 Piscium, BD+23° 158, CCDM J01137+2435A, FK5 2082, GC 1474, HD 7318, HIP 5742, HR 360, IDS 01083+2403, PPM 90580, SAO 74571, WDS J01137+2435A.
Database references

Phi Piscium (Phi Psc, φ Piscium, φ Psc) is a binary star 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.[1] 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.[4] The star system has a period of about 20½ years and has a notably high eccentricity of 0.815.[3]


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.)[5]


  1. ^ a b "* phi Psc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved October 1, 2007. 
  2. ^ a b Ryon, Jenna; et al. (August 2009), "Comparing the Ca ii H and K Emission Lines in Red Giant Stars", Publications of the Astronomical Society of the Pacific, 121 (882): 842, arXiv:0907.3346Freely accessible, Bibcode:2009PASP..121..842R, doi:10.1086/605456. 
  3. ^ a b R.F. Griffin; G.H. Herbig (1991). "Spectroscopic binary orbits from photoelectric radial velocities. Paper 99: Phi PISCIUM". The Observatory. 111: 155–162. Bibcode:1991Obs...111..155G. 
  4. ^ R.F. Griffin; G.H. Herbig (1991). "Spectroscopic binary orbits from photoelectric radial velocities. Paper 100: Phi PISCIUM B". The Observatory. 111: 201–219. Bibcode:1991Obs...111..201G. 
  5. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 19 日