Gamma Corvi (γ Corvi, abbreviated Gamma Crv, γ Crv) is a binary star and the brightest star in the southern constellationofCorvus, having an apparent visual magnitude of 2.59.[12] The system's two components are designated Gamma Corvi A (officially named Gienah/ˈdʒiːnə/, traditionally the name of the system)[13][14] and Gamma Corvi B, whose magnitude is 9.7 and which is 1.1 arcseconds away from Gamma Corvi A.[15] The distance to this system has been measured directly using the parallax technique, yielding an estimated 154 light-years (47parsecs) from the Sun.[1]
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.[17] The star Epsilon Cygni also bore this traditional name and Gamma Corvi was referred to as Gienah CorviorGienah Ghurab to distinguish it from this star in Cygnus.
In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[18] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[19] It approved the name Gienah for the component Gamma Corvi A on 6 November 2016 and Aljanah for Epsilon Cygni Aa on 30 June 2017. They are both now so included in the List of IAU-approved Star Names.[14]
Al-janāħ al-ghirāb al-yamanorDjenah al Ghyrab al Eymen appeared in the catalog of stars in the Calendarium of Al Achsasi Al Mouakket, which was translated into LatinasDextra ala Corvi.[20]
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.[6] The radius of the star is calculated at 4.026 R☉.[7][a] It has a blue-white hue.[23] The spectrum of this star displays an anomalously higher than normal abundance of the elements mercury and manganese, making this a Mercury-manganese star.[24] However, there are other elements that show large over or under abundances.[8] This chemical peculiarity in an otherwise stable stellar atmosphere is most likely caused by separation of the elements through diffusion and gravitational settling.[24]
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.[6] The photometry for Gamma Corvi B suggests a stellar classification in the range K5–M5 V.[10]
^ abcdCousins, A. W. J. (1984), "Standardization of Broadband Photometry of Equatorial Standards", South African Astronomical Observatory Circulars, 8: 59, Bibcode:1984SAAOC...8...59C
^ abHouk, 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, 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H
^ abFremat, 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
^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
^Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN978-1-931559-44-7.
^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].
^ abAdelman, 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
