Alpha Piscium

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Alpha Piscium
Pisces IAU.svg
Red circle.svg

Location of α Piscium (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Pisces
Right ascension 00h 48m 40.94433s[1]
Declination +07° 35′ 06.2926″[1]
Apparent magnitude (V) 3.82 (4.33 + 5.23)[2]
Characteristics
Spectral type kA0hA7 Sr + kA2hF2mF2 (IV)[3]
Astrometry
Proper motion (μ) RA: +83.10[1] mas/yr
Dec.: −49.58[1] mas/yr
Parallax (π) 10.48 ± 0.22[1] mas
Distance 311 ± 7 ly
(95 ± 2 pc)
Absolute magnitude (MV) +0.50[4]
Orbit[5]
Period (P) 3267.4 yr
Semi-major axis (a) 7.4″
Eccentricity (e) 0.465
Inclination (i) 113.4°
Longitude of the node (Ω) 3.70°
Periastron epoch (T) 2188.6
Argument of periastron (ω)
(secondary)
147.9°
Details
α Psc A
Rotational velocity (v sin i) 81[6] km/s
α Psc B
Rotational velocity (v sin i) 84[6] km/s
Other designations
Alrischa, Kaitain, Okda, α Psc, 113 Piscium, BD+02° 317, FK5 28, HIP 9487, SAO 110291, WDS J02020+0246AB[7]
α Psc A: HD 12447, HR 596[8]
α Psc B: HD 12446, HR 595[9]
Database references
SIMBAD α Psc
α Psc A
α Psc B

Alpha Piscium (α Piscium), also named Alrescha,[10] is a binary star[5] system in the equatorial constellation of Pisces.

Properties[edit]

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.[11]

Nomenclature[edit]

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".[12] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[13] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[14] 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.)[15]

References[edit]

  1. ^ a b c d e van Leeuwen, F. (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. ^ 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. 
  3. ^ Gray, R. O.; Garrison, R. F. (July 1989), "The Late A-Type Stars: Refined MK Classification, Confrontation with Stroemgren Photometry, and the Effects of Rotation", Astrophysical Journal Supplement, 70: 623, Bibcode:1989ApJS...70..623G, doi:10.1086/191349. 
  4. ^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971Freely accessible, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015. 
  5. ^ a b Hartkopf, W. I.; et al. (June 30, 2006), Sixth Catalog of Orbits of Visual Binary Stars, United States Naval Observatory, retrieved 2017-06-02. 
  6. ^ a b Royer, F.; et al. (October 2002), "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i", Astronomy and Astrophysics, 393: 897–911, arXiv:astro-ph/0205255Freely accessible, Bibcode:2002A&A...393..897R, doi:10.1051/0004-6361:20020943. 
  7. ^ "alf Psc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-04. 
  8. ^ "alf Psc A". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-04. 
  9. ^ "alf Psc B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-04. 
  10. ^ Mamajek, Eric; et al., IAU Catalog of Star Names, IAU Division C Working Group on Star Names, retrieved 28 July 2016. 
  11. ^ Kaler, James B., "ALRESCHA (Alpha Piscium)", Stars, University of Illinois, retrieved 2012-04-06. 
  12. ^ Allen, Richard Hinckley, Star-names and their meanings, G. E. Stechert, pp. 342−343. 
  13. ^ Division C WG Star Names, IAU Working Group on Star Names (WGSN), retrieved 22 May 2016. 
  14. ^ Mamajek, Eric; et al. (July 2016), Bulletin of the IAU Working Group on Star Names, No. 1 (PDF), IAU Division C: Education, Outreach and Heritage., retrieved 28 July 2016. 
  15. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 19 日