Gamma Circini
Variable star in the constellation Circinus
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Gamma Circini is a star system in the constellation Circinus. Its name is a Bayer designation that is Latinized from γ Circini, and abbreviated Gamma Cir or γ Cir. This was noted as a double star by Herschel in 1835, who estimated the separation as 1 arc second.[11] It is visible to the naked eye as a point of light with a combined apparent visual magnitude of 4.51.[3] Based upon an annual parallax shift of 7.27 mas,[2] it is about 450 light-years away.
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Circinus[1] |
| Right ascension | 15h 23m 22.64294s[2] |
| Declination | −59° 19′ 14.8131″[2] |
| Apparent magnitude (V) | 4.51[3] (4.94 + 5.73)[4] |
| Characteristics | |
| Spectral type | B5 IV[5] + F8 V[3] |
| Variable type | Be[6] |
| Astrometry | |
| Radial velocity (Rv) | 16.90±1.78[7] km/s |
| Proper motion (μ) | RA: −12.97 mas/yr[2] Dec.: −34.24 mas/yr[2] |
| Parallax (π) | 7.27±0.81 mas[2] |
| Distance | approx. 450 ly (approx. 140 pc) |
| Absolute magnitude (MV) | −1.18[1] |
| Orbit[5] | |
| Period (P) | 258 yr |
| Semi-major axis (a) | 2.576″ |
| Eccentricity (e) | 0.931 |
| Details | |
| γ Cir A | |
| Mass | 6.0±0.3[8] M☉ |
| Temperature | 15,135[9] K |
| Age | 63.1±19.6[8] Myr |
| γ Cir B | |
| Temperature | 4,786[9] K |
| Other designations | |
| γ Cir, CPD−58°5908, HIP 75323, HR 5704, SAO 242463[10] | |
| γ Cir A: HD 136415 | |
| γ Cir B: HD 136416 | |
| Database references | |
| SIMBAD | γ Cir AB |
| γ Cir A | |
| γ Cir B | |
This is a wide binary star system and may even be a triple star.[9] The two visible components orbit each other with a preliminary estimated period of 258 years and a large eccentricity of 0.931.[5] As of 2014, the visible components have an angular separation of 0.80 arc seconds on a position angle of 359°.[4]
The primary star, component A, is a B-type subgiant star with a stellar classification of B5 IV.[5] Based upon isochrone curve fitting it is hypothesized to be a pair of matching B5 stars,[9] and is a Be variable with an uncertain maximum.[6] It has an effective temperature of 15,135[9] K and an estimated mass six[8] times that of the Sun. The companion, component B, is an F-type main-sequence star with a stellar classification of F8 V.[3] It has an effective temperature of 4,786[9] K.