Epoch J2000 Equinox J2000
|Right ascension||12h 15m 48.37081s|
|Declination||–17° 32′ 30.9496″|
|Apparent magnitude (V)||2.585|
|Spectral type||B8 III|
|U−B color index||–0.344|
|B−V color index||–0.111|
|Radial velocity (Rv)||-4.2 km/s|
|Proper motion (μ)||RA: –158.61 mas/yr
Dec.: +21.86 mas/yr
|Parallax (π)||21.23 ± 0.20 mas|
|Distance||154 ± 1 ly
(47.1 ± 0.4 pc)
|γ Crv A|
−0.3 or 5.7±0.3 M☉
|Surface gravity (log g)||3.72±0.20 cgs|
|Rotational velocity (v sin i)||30 km/s|
|γ Crv B|
Gamma Corvi (γ Crv, γ Corvi) is the brightest star in the southern constellation of Corvus, having an apparent visual magnitude of 2.6. Its traditional name is Gienah, which it shares with Epsilon Cygni. The name "Gienah Corvi", or "Gienah Ghurab", may be used to distinguish it from this star in Cygnus. The distance to this star has been measured directly using the parallax technique, yielding an estimated 154 light-years (47 parsecs) from Earth.
Also called Gienah, Gamma Corvi is the brightest star in Corvus at magnitude 2.59. It is a giant star with a stellar classification of B8 III. It has around five times the Sun's radius, with mass estimates ranging from 4.2 to 5.7 times the mass of the Sun. Gamma Corvi is radiating 1,260 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 15,900 K, giving it a blue-white hue. The spectrum of this star displays an anomalously higher than normal abundance of the elements mercury and manganese, making this a Mercury-manganese star. However, there are other elements that show large over or under abundances. This chemical peculiarity in an otherwise stable stellar atmosphere is most likely caused by separation of the elements through diffusion and gravitational settling.
Gamma Corvi 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. The photometry for this star suggests a stellar classification in the range K5–M5 V.
Etymology and cultural significance
"Gienah" derives 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. Al-janāħ al-ghirāb al-yaman or Djenah al Ghyrab al Eymen appeared in the catalogue of stars in the Calendarium of Al Achsasi Al Mouakket, which was translated into Latin as Dextra ala Corvi.
In Chinese, 軫宿 (Zhěn Sù), meaning Chariot (asterism), refers to an asterism consisting of γ Corvi, ε Corvi, δ Corvi and β Corvi. Consequently, γ Corvi itself is known as 軫宿一 (Zhěn Sù yī, English: the First Star of Chariot.).
In astrology, Gienah 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."
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