Alpha Piscium

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Alpha Piscium
Diagram showing star positions and boundaries of the Pisces constellation and its surroundings
Cercle rouge 100%.svg

Location of α Piscium(circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Pisces
Right ascension 02h 02m 02.81972s[1]
Declination +02° 45′ 49.5410″[1]
Apparent magnitude (V) 3.82[2] (+4.33 + 5.23)[3]
Distance 139 ± 1.6 ly
(46.2 ± 0.5[1] pc)
Spectral type A0pSiSr + A3m[3]
Other designations
Alrischa, Alrescha, Kaitain, Okda, α Piscium, α Psc, Alpha Psc, 113 Piscium, BD+02 317, CCDM J02020+0246AB, HD 12447/12446, HIP 9487, HR 595/596, IDS 01569+0217 AB / 02020+0246, SAO 110291, WDS J02020+0246AB.[2]

Alpha Piscium (α Piscium, abbreviated Alpha Psc, α Psc), also named Alrescha,[4] is a binary star in the equatorial constellation of Pisces.


The system is about 139 light years from the Sun. It comprises a close binary with angular separation of presently 1.8" between the components. The main star or primary is of magnitude +4.33 and spectral type A0p, while the companion or secondary is magnitude 5.23 and belongs to spectral class A3m. The two stars take more than 700 years to orbit one another and they will make their closest approach to each other around 2060. One or both of the stars may be a spectroscopic binary as well. The stars have masses of 2.3 and 1.8 solar masses respectively and shine with a total luminosity of 31 and 12 times that of the Sun.[5]


α Piscium (Latinised to Alpha Piscium) is the star's Bayer designation.

The system bore the traditional name Alrescha (alternatively Al Rescha, Alrischa, Alrisha) derived from the Arabic الرشآء al-rišā’ "the well rope" and less commonly Kaitain and Okda, the latter from the Arabic عقدة ‘uqdah "knot".[6] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[7] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[8] included a table of the first two batches of names approved by the WGSN; which included Alrescha for this star.

In Chinese, 外屏 (Wài Píng), meaning Outer Fence, refers to an asterism consisting of Alpha Piscium, Delta Piscium, Epsilon Piscium, Zeta Piscium, Mu Piscium, Nu Piscium and Xi Piscium. Consequently, Alpha Piscium itself is known as 外屏七 (Wài Píng qī, English: the Seventh Star of Outer Fence.)[9]


  1. ^ a b c van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. 
  2. ^ a b "alf Psc -- Variable Star of alpha2 CVn type", SIMBAD Astronomical Object Database, Centre de Données astronomiques de Strasbourg. 
  3. ^ a b Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819. 
  4. ^ "IAU Catalog of Star Names". Retrieved 28 July 2016. 
  5. ^ Kaler, James B., "ALRESCHA (Alpha Piscium)", Stars, University of Illinois, retrieved 2012-04-06. 
  6. ^ Allen, Richard Hinckley (1899), Star-names and their meanings, G. E. Stechert, p. 506. 
  7. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016. 
  8. ^ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016. 
  9. ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 19 日