Gamma Circini
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Circinus |
| Right ascension | 15h 23m 22.64294s |
| Declination | −59° 19′ 14.8131″ |
| Apparent magnitude (V) | 4.51 (4.94 + 5.73) |
| Characteristics | |
| Spectral type | B5 IV + F8 V |
| Variable type | Be |
| Astrometry | |
| Radial velocity (Rv) | 16.90±1.78 km/s |
| Proper motion (μ) | RA: −12.97 mas/yr Dec.: −34.24 mas/yr |
| Parallax (π) | 7.27±0.81 mas |
| Distance | approx. 450 ly (approx. 140 pc) |
| Absolute magnitude (MV) | −1.18 |
| Orbit | |
| Period (P) | 258 yr |
| Semi-major axis (a) | 2.576″ |
| Eccentricity (e) | 0.931 |
| Details | |
| γ Cir A | |
| Mass | 6.0±0.3 M☉ |
| Temperature | 15,135 K |
| Age | 63.1±19.6 Myr |
| γ Cir B | |
| Temperature | 4,786 K |
| Other designations | |
| γ Cir, CPD−58°5908, HIP 75323, HR 5704, SAO 242463 | |
| γ Cir A: HD 136415 | |
| γ Cir B: HD 136416 | |
| Database references | |
| SIMBAD | γ Cir AB |
| γ Cir A | |
| γ Cir B | |
Gamma Circini, Latinized from γ Circini, is a star system in the constellation Circinus. It was noted as a double star by Herschel in 1835, who estimated the separation as 1 arc second. It is visible to the naked eye with an apparent visual magnitude of 4.51. Based upon an annual parallax shift of 7.27 mas, it is about 450 light-years away.
This is a wide binary star system and may even be a triple star. The two visible components orbit each other with a preliminary estimated period of 258 years and a large eccentricity of 0.931. As of 2014, the visible components have an angular separation of 0.80 arc seconds on a position angle of 359°.
The primary star, component A, is a B-type subgiant star with a stellar classification of B5 IV. Based upon isochrone curve fitting it is hypothesized to be a pair of matching B5 stars, and is a Be variable with an uncertain maximum. It has an effective temperature of 15,135 K and an estimated mass six times that of the Sun. The companion, component B, is an F-type main-sequence star with a stellar classification of F8 V. It has an effective temperature of 4,786 K.