Zeta Piscium

Zeta Piscium (ζ Piscium, abbreviated Zet Psc, ζ Psc) is a quintuple[2] star system in the zodiac constellation of Pisces. Based upon parallax measurements obtained during the Hipparcos mission, it is located roughly 170 light-years (52 parsecs) distant from the Sun.[1]

Zeta Piscium
Location of ζ Piscium (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Pisces
ζ Psc A
Right ascension  01h 13m 45.17477s[1]
Declination +07° 34′ 31.2745″[1]
Apparent magnitude (V) 5.28[2]
ζ Psc B
Right ascension  01h 13m 43.88735s[1]
Declination +07° 34′ 42.1765″[1]
Apparent magnitude (V) 6.43[2]
Characteristics
Spectral type A7IV + A7IV + F7V + G7V + ?[2]
Astrometry
ζ Psc A
Proper motion (μ) RA: +145.00[1] mas/yr
Dec.: −55.69[1] mas/yr
Parallax (π)18.76 ± 2.76[1] mas
Distanceapprox. 170 ly
(approx. 53 pc)
Absolute magnitude (MV)1.97[3]
ζ Psc B
Proper motion (μ) RA: +181.78[1] mas/yr
Dec.: −40.34[1] mas/yr
Details[4]
ζ Psc A
Mass2.07±0.13 M☉
Luminosity27.4 L☉
Temperature7,345 K
Rotational velocity (v sin i)196 km/s
ζ Psc B
Metallicity [Fe/H]0.18[3] dex
Other designations
Revati, ζ Psc, 86 Piscium
ζ Psc A: BD+06° 174, FK5 1033, HD 7344, HIP 5737, HR 361, SAO 109739, WDS J01137+0735A[5]
ζ Psc B: BD+06° 175, HD 7345, HIP 5743, HR 362, SAO 109740, WDS J01137+0735BC[6]
Database references
SIMBADdata

The system consists of a binary star (Zeta Piscium A) and a triple star system (BC), the latter consisting of a spectroscopic binary (B) and a single star (C). A's two components are themselves designated Zeta Piscium Aa (officially named Revati /ˈreɪvəti/)[7] and Ab; B's two components as Ba and Bb.

As the star system is 0.21° south of the ecliptic,[8] it can be eclipsed (occulted) by the moon, when close to or at one of its two nodes of its orbit;[9] and is eclipsed by the sun from about 8-10 April.[10]

Nomenclature

ζ Piscium (Latinised to Zeta Piscium) is the system's Bayer designation. The designations of the three constituents as Zeta Piscium A, B and C, and those of A's and B's components - Zeta Piscium Aa, Ab, Ba and Bb - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[11]

The system is identified with Revati (रेवती rēvatī, Sanskrit pronunciation: [ˈɽeːʋɐt̪iː]), one of the Indian nakshatra (lunar mansions). In 2016, the IAU organized a Working Group on Star Names (WGSN)[12] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[13] It approved the name Revati for the constituent Zeta Piscium A on 30 June 2017 and it is now so included in the List of IAU-approved Star Names.[7] Where a component letter is not explicitly listed, the WGSN says that the name should be understood to be attributed to the brightest component by visual brightness (component Aa in this case).[14]

In Chinese, 外屏 (Wài Píng), meaning Outer Fence, refers to an asterism consisting of Zeta Piscium, Delta Piscium, Epsilon Piscium, Mu Piscium, Nu Piscium, Xi Piscium and Alpha Piscium. Consequently, the Chinese name for Zeta Piscium itself is 外屏三 (Wài Píng sān, English: the Third Star of Outer Fence.)[15]

Properties

The primary, Zeta Piscium A, is a pair of A-type subgiant stars with an angular separation of 0.15 arcseconds and visual magnitude 5.28.[2]

The secondary, Zeta Piscium B, is a spectroscopic binary with a period of 9.075 days and an eccentricity of 0.04. Together, components Ba and Bb have a combined visual magnitude of 6.43 and lie at an angular separation of 22.9 arcseconds from the primary. They are a F-type main sequence star and a G-type main sequence star, respectively.

The tertiary and fifth component, Zeta Piscium C, is a magnitude 12.2 star at an angular separation 1.0 arc seconds from component B.[2]

Together the star system has an apparent magnitude of +4.9.[8]

gollark: What?
gollark: Also, "invariants" is a *great* word.
gollark: You are meant to have code around the `unsafe` bit to check invariants.
gollark: (outside `unsafe` blocks)
gollark: Raw pointers == banned.

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.
  2. 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.
  3. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  4. Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691.
  5. "zet Psc A". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-07-31.
  6. "zet Psc B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-07-31.
  7. "Naming Stars". IAU.org. Retrieved 16 December 2017.
  8. John Pratt's stars re-publication by Dr J.P. Pratt (Doctor of Astronomy, University of Arizona) of sidereal coordinate data. Note: possibly a non-book published source.
  9. Meyer, C.; et al. (1995), "Observations of lunar occultations at Observatoire de la Cote d'Azur", Astronomy and Astrophysics Supplement, 110: 107, Bibcode:1995A&AS..110..107M.
  10. In the Sky Earth astronomy reference utility showing the ecliptic and relevant date as at J2000 - present.
  11. Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
  12. "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  13. "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Retrieved 2018-07-14.
  14. "Bulletin of the IAU Working Group on Star Names, No. 2" (PDF). Retrieved 12 October 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
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