Gamma Centauri
 Location of γ Centauri (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Centaurus |
| Right ascension | 12h 41m 31.04008s |
| Declination | −48° 57′ 35.5375″ |
| Apparent magnitude (V) | +2.17 (+2.85/+2.95) |
| Characteristics | |
| Spectral type | A1IV+ (A0III/A0III) |
| U−B color index | −0.01 |
| B−V color index | −0.01 |
| Astrometry | |
| Radial velocity (Rv) | −5.5 km/s |
| Proper motion (μ) |
RA: −185.72 mas/yr Dec.: +5.79 mas/yr |
| Parallax (π) | 25.06 ± 0.28mas |
| Distance | 130 ± 1 ly (39.9 ± 0.4 pc) |
| Absolute magnitude (MV) | –0.81 |
| Orbit | |
| Companion | γ Centauri B |
| Period (P) | 83.57 yr |
| Semi-major axis (a) | 0.869" |
| Eccentricity (e) | 0.793 |
| Inclination (i) | 113.7° |
| Longitude of the node (Ω) | 2.6° |
| Periastron epoch (T) | 1931.25 |
|
Argument of periastron (ω) (secondary) |
187.9° |
| Details | |
| Mass | 2.91 M☉ |
| Surface gravity (log g) | 3.52 cgs |
| Temperature | 9,082 K |
| Other designations | |
| Database references | |
| SIMBAD | data |
Gamma Centauri (γ Cen, γ Centauri) is a star in the southern constellation Centaurus. It has the proper name Muhlifain, 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 located about 130 light-years (40 parsecs) from Earth. The combined apparent visual magnitude of the pair is +2.17, although individually they are third magnitude stars. The stellar classification of the pair is A1IV+, suggesting they are A-type subgiant stars in the process of becoming giants. Individually, their stellar classifications are sometimes listed as A0III, which would mean they have already become giants.
In 2000, the pair had an angular separation of 1.217 arcseconds with a position angle of 351.9°. Their positions have been observed since 1897, which is long enough to estimate an orbital period of 84.5 years and a semimajor axis of 0.93 arcseconds. At the distance of this system, this is equivalent to a linear distance of about 93 Astronomical Units. The star Tau Centauri is relatively close to Gamma Centauri, with an estimated separation of 1.72 light-years (0.53 pc).
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. Consequently, γ Centauri itself is known as 庫樓七 (Kù Lóu qī, English: the Seventh Star of Arsenal.)
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