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]
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
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]
Distance400 ± 10 ly
(123 ± 3 pc)
Absolute magnitude (MV)−0.67[3]
Orbit[4]
Companionφ 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
Radius23.63+0.66
−1.36[1] R☉
Luminosity249.6±7.1[1] L☉
Surface gravity (log g)2.75[2] cgs
Temperature4,720+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
SIMBADdata

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]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. McWilliam, Andrew (December 1990), "High-resolution spectroscopic survey of 671 GK giants", Astrophysical Journal Supplement Series (PDF), 74: 1075–1128, Bibcode:1990ApJS...74.1075M, doi:10.1086/191527.
  3. 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:0907.3346, Bibcode:2009PASP..121..842R, doi:10.1086/605456, S2CID 17821279.
  4. Griffin, R. F.; Herbig, G. H. (1991). "Spectroscopic binary orbits from photoelectric radial velocities. Paper 99: Phi PISCIUM". The Observatory. 111: 155–162. Bibcode:1991Obs...111..155G.
  5. "* phi Psc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved October 1, 2007.
  6. Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.
  7. 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.
  8. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 19 日
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