Gamma Corvi

Gamma Corvi


Location of γ Crv (circled)

Observation data
Epoch J2000      Equinox J2000
Constellation Corvus
Right ascension 12h 15m 48.37081s[1]
Declination –17° 32′ 30.9496″[1]
Apparent magnitude (V) 2.585[2]
Characteristics
Spectral type B8 III[3]
U−B color index –0.344[2]
B−V color index –0.111[2]
Astrometry
Radial velocity (Rv)-4.2[4] km/s
Proper motion (μ) RA: –158.61[1] mas/yr
Dec.: +21.86[1] mas/yr
Parallax (π)21.23 ± 0.20[1] mas
Distance154 ± 1 ly
(47.1 ± 0.4 pc)
Details
γ Crv A
Mass4.2+0.4
−0.3[5] M☉
Rotational velocity (v sin i)30[6] km/s
Age160+40
−30[5] Myr
γ Crv B
Mass0.8[7] M☉
Other designations
4 Corvi, BD–16 3424, FK5 457, HD 106625, HIP 59803, HR 4662, SAO 157176.[8]

Gamma Corvi (γ Corvi, abbreviated Gamma Crv, γ Crv) is a binary star and the brightest star in the southern constellation of Corvus, having an apparent visual magnitude of 2.59.[9] The system's two components are designated Gamma Corvi A (also named Gienah[10]) and Gamma Corvi B. The distance to this system has been measured directly using the parallax technique, yielding an estimated 154 light-years (47 parsecs) from the Sun.[1]

Nomenclature

γ Corvi (Latinised to Gamma Corvi) is the system's Bayer designation. The designation of the components - Gamma Corvi A and B - derives from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[11]

Gamma Corvi bore the traditional name of Gienah derived from Arabic, from Ulugh Beg's الجناح الغراب اليمن al-janāħ al-ghirāb al-yaman, meaning "the right wing of the crow", although on modern charts it marks the left wing. The star Epsilon Cygni also bore this traditional name and Gamma Corvi was referred to as Gienah Corvi or Gienah Ghurab to distinguish it from this star in Cygnus.

In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[12] to catalogue and standardize proper names for stars. The WGSN states that in the case of multiple stars the name should be understood to be attributed to the brightest component by visual brightness.[13] The WGSN approved the name Gienah for Gamma Corvi A on 6 November 2016 and it is now so entered in the IAU Catalog of Star Names.[10]

Al-janāħ al-ghirāb al-yaman or Djenah al Ghyrab al Eymen appeared in the catalog of stars in the Calendarium of Al Achsasi Al Mouakket, which was translated into Latin as Dextra ala Corvi.[14]

In Chinese, 軫宿 (Zhěn Sù), meaning Chariot (asterism), refers to an asterism consisting of Gamma Corvi, Epsilon Corvi, Delta Corvi and Beta Corvi.[15] Consequently, Gamma Corvi itself is known as 軫宿一 (Zhěn Sù yī, English: the First Star of Chariot.).[16]

Properties

Gamma Corvi A is a giant star with a stellar classification of B8 III[3][2] and has approximately 4.2 times the mass of the Sun.[5] It has a blue-white hue.[17] The spectrum of this star displays an anomalously higher than normal abundance of the elements mercury and manganese, making this a Mercury-manganese star.[18] However, there are other elements that show large over or under abundances.[19] This chemical peculiarity in an otherwise stable stellar atmosphere is most likely caused by separation of the elements through diffusion and gravitational settling.[18]

It has a confirmed stellar companion with a mass of about 0.8 times the Sun's, which may be orbiting at a separation of around 50 AU over a 158 year period.[5] The photometry for Gamma Corvi B suggests a stellar classification in the range K5–M5 V.[7]

In culture

In astrology, Gamma Corvi is supposed to have a similar effect to Mars and Saturn, tending to promote greed and craftiness. It was one of the medieval Behenian stars, associated with onyx, burdock, and a crow-like kabbalistic symbol . In this context it is sometimes referred to as Ala Corvi, "the wing of the crow or raven."

References

  1. 1 2 3 4 5 6 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. 1 2 3 4 Cousins, A. W. J. (1984), "Standardization of Broadband Photometry of Equatorial Standards", South African Astronomical Observatory Circulars, 8: 59, Bibcode:1984SAAOC...8...59C
  3. 1 2 Houk, Nancy (1978), "Michigan catalogue of two-dimensional spectral types for the HD stars", Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4, Ann Arbor: Dept. of Astronomy, University of Michigan, 4, Bibcode:1988MSS...C04....0H
  4. ↑ Wilson, Ralph Elmer (1953), "General Catalogue of Stellar Radial Velocities", Washington, Washington: Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W
  5. 1 2 3 4 Janson, Markus; et al. (August 2011), "High-contrast Imaging Search for Planets and Brown Dwarfs around the Most Massive Stars in the Solar Neighborhood", The Astrophysical Journal, 736 (2): 89, arXiv:1105.2577Freely accessible, Bibcode:2011ApJ...736...89J, doi:10.1088/0004-637X/736/2/89
  6. ↑ Abt, Helmut A.; Levato, Hugo; Grosso, Monica (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal, 573 (1): 359–365, Bibcode:2002ApJ...573..359A, doi:10.1086/340590
  7. 1 2 Roberts, Lewis C., Jr.; Turner, Nils H.; ten Brummelaar, Theo A. (February 2007), "Adaptive Optics Photometry and Astrometry of Binary Stars. II. A Multiplicity Survey of B Stars", The Astronomical Journal, 133 (2): 545–552, Bibcode:2007AJ....133..545R, doi:10.1086/510335
  8. ↑ "GIENAH CORVI -- Variable Star", SIMBAD Astronomical Object Database, Centre de Données astronomiques de Strasbourg, retrieved 2010-05-02
  9. ↑ Kaler, James B. (Jim) (2004), "Gienah Corvi", Stars, University of Illinois, retrieved 18 March 2015
  10. 1 2 "IAU Catalog of Star Names". Retrieved 23 November 2016.
  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:1012.0707Freely accessible [astro-ph.SR].
  12. ↑ IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.
  13. ↑ "Bulletin of the IAU Working Group on Star Names, No. 2" (PDF). Retrieved 12 October 2016.
  14. ↑ Knobel, E. B. (June 1895), "Al Achsasi Al Mouakket, on a catalogue of stars in the Calendarium of Mohammad Al Achsasi Al Mouakket", Monthly Notices of the Royal Astronomical Society, 55 (8): 429, Bibcode:1895MNRAS..55..429K, doi:10.1093/mnras/55.8.429
  15. ↑ (Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  16. ↑ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.
  17. ↑ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, retrieved 2012-01-16
  18. 1 2 Adelman, S. J.; et al. (February 2006), "Elemental abundance analyses with DAO spectrograms. XXIX. The mercury-manganese stars 53 Tau, β Tau, γ Crv, and υ Her", Astronomy and Astrophysics, 447 (2): 685–690, Bibcode:2006A&A...447..685A, doi:10.1051/0004-6361:20053581
  19. ↑ Fremat, Y.; Houziaux, L. (April 1997), "Elemental abundances in the Hg-Mn star γ Corvi", Astronomy and Astrophysics, 320: 580–585, Bibcode:1997A&A...320..580F
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