Gamma Centauri

Gamma Centauri A/B

Observation data Epoch J2000      Equinox J2000
Constellation	Centaurus
Right ascension	12h 41m 31.0s
Declination	−48° 57′ 35″
Apparent magnitude (V)	+2.2 (+2.9/+2.9)
Characteristics
Spectral type	A0III/A0III
U−B color index	−0.01
B−V color index	−0.01
Variable type	none
Astrometry
Radial velocity (Rv)	−6 km/s
Proper motion (μ)	RA: −187.28 mas/yr Dec.: −1.20 mas/yr
Parallax (π)	25.01 ± 1.01 mas
Distance	130.4 ly (40.0 pc)
Absolute magnitude (MV)	−0.8 (−0.1/−0.1)
Details
Mass	2.8 M☉
Radius	36.5 R☉
Luminosity	90/star L☉
Temperature	9,300 K
Rotation	~81 km/s.
Orbit
Companion	γ Centauri B
Period (P)	84.5 yr
Semimajor axis (a)	34AU=0.86"
Eccentricity (e)	0.79
Inclination (i)	114°
Longitude of the node (Ω)	2°
Periastron epoch (T)	1931.2
Other designations
Muhlifain, HR 4819, HD 110304, CD−48°7597, SAO 223603, WDS 12415-4858, HIP 61932, GC 17262, CCDM J12415-4858
Database references
SIMBAD	data

Gamma Centauri (γ Cen, γ Centauri) is a star in the constellation Centaurus. It has the proper name Muhlifain,^[1] not to be confused with Muliphein, which is γ Canis Majoris; both names derive from the same Arabic root.

Gamma Centauri is a double star approximately 130 light years from Earth, which consists of two spectral type A0 stars each of apparent magnitude +2.9. For the resolution of the double star system a telescope of at least 15 centimeters in aperture is necessary. They have an orbital period of 83 years.

Year	Angular separation	Position angle
1990	1.4″	353°
2000	1.0″	347°
2005	0.7″	341°
2010	0.4″	324°

Etymology

In Chinese, 庫樓 (Kù Lóu), meaning Arsenal, refers to an asterism consisting of γ Centauri, ζ Centauri, η Centauri, θ Centauri, 2 Centauri, HD 117440, ξ¹ Centauri, τ Centauri, D Centauri and σ Centauri.^[2] Consequently, γ Centauri itself is known as 庫樓七 (Kù Lóu qī, English: the Seventh Star of Arsenal.)^[3]

The people of Aranda and Luritja tribe around Hermannsburg, Central Australia named Iritjinga, "The Eagle-hawk", a quadrangular arrangement comprising this star, δ Cen (Ma Wei), δ Cru (Palida) and γ Cru (Gacrux), .^[4]

References

1. ^ Kunitzsch, P., Arabische Sternnamen in Europa, Otto Harrassowitz, Wiesbaden, p.188.
2. ^ (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.
3. ^ (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.
4. ^ p. 8, Explorers of the southern sky: a history of Australian astronomy, Raymond Haynes, Cambridge, Cambridge University Press, 1996.