Chi Piscium

Chi Piscium (χ Piscium) is a solitary,[9] orange-hued star in the zodiac constellation of Pisces. It can be seen with the naked eye, having an apparent visual magnitude of +4.64.[2] Based upon an annual parallax shift of 8.50 mas as seen from Earth,[1] it is located about 384 light years from the Sun.

Chi Piscium
Location of χ Piscium (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Pisces
Right ascension 01h 11m 27.21877s[1]
Declination +21° 02′ 04.7406″[1]
Apparent magnitude (V) +4.64[2]
Characteristics
Spectral type G8.5 III[3]
U−B color index +0.83[2]
B−V color index +1.02[2]
Astrometry
Radial velocity (Rv)+15.04±0.21[4] km/s
Proper motion (μ) RA: +39.32[1] mas/yr
Dec.: −10.48[1] mas/yr
Parallax (π)8.50 ± 0.21 mas[1]
Distance384 ± 9 ly
(118 ± 3 pc)
Absolute magnitude (MV)−1.13[5]
Details[6]
Mass3.17±0.23 M☉
Radius20.65±0.57 R☉
Luminosity209.2±10.5 L☉
Surface gravity (log g)2.33±0.05 cgs
Temperature4,835±28 K
Metallicity [Fe/H]−0.15±0.10 dex
Rotational velocity (v sin i)10[7] km/s
Age380±100 Myr
Other designations
χ Psc, 84 Piscium, BD+20° 172, FK5 1032, HD 7087, HIP 5571, HR 351, SAO 74544[8]
Database references
SIMBADdata

This is an evolved G-type giant star with a stellar classification of G8.5 III.[3] There is a 94%[6] chance that it is on the horizontal branch and is a red clump star,[10] which means it is generating energy through helium fusion at its core. Chi Piscium is estimated to have 3.17 times the mass of the Sun, nearly 21 times the solar radius, and shines with 209 times the Sun's luminosity. It is around 380 million years old.[6]

Naming

In Chinese, 奎宿 (Kuí Sù), meaning Legs (asterism), refers to an asterism consisting of χ 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, φ Piscium and ψ¹ Piscium. Consequently, the Chinese name for χ Piscium itself is 奎宿十五 (Kuí Sù shíwǔ, English: the Fifteenth Star of Legs.)[11]

References
  1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
  2. Argue, A. N. (1966), "UBV photometry of 550 F, G and K type stars", Monthly Notices of the Royal Astronomical Society, 133 (4): 475–493, Bibcode:1966MNRAS.133..475A, doi:10.1093/mnras/133.4.475.
  3. Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373.
  4. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
  5. Takeda, Yoichi; Sato, Bun'ei; Murata, Daisuke (August 2008), "Stellar Parameters and Elemental Abundances of Late-G Giants", Publications of the Astronomical Society of Japan, 60 (4): 781–802, arXiv:0805.2434, Bibcode:2008PASJ...60..781T, doi:10.1093/pasj/60.4.781, S2CID 16258166.
  6. Reffert, Sabine; et al. (2015), "Precise radial velocities of giant stars. VII. Occurrence rate of giant extrasolar planets as a function of mass and metallicity", Astronomy & Astrophysics, 574: A116, arXiv:1412.4634, Bibcode:2015A&A...574A.116R, doi:10.1051/0004-6361/201322360, S2CID 59334290. Values are for the slightly higher probability horizontal branch model fit.
  7. Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago, 239 (1): 1, Bibcode:1970CoAsi.239....1B.
  8. "chi Psc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-07-23.{{cite web}}: CS1 maint: postscript (link)
  9. 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.
  10. Valentini, M.; Munari, U. (November 2010), "A spectroscopic survey of faint, high-Galactic-latitude red clump stars. I. The high resolution sample", Astronomy and Astrophysics, 522: A79, arXiv:1007.0207, Bibcode:2010A&A...522A..79V, doi:10.1051/0004-6361/201014870, S2CID 119156545.
  11. (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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