Gamma Circini

Gamma Circini (γ Cir) is a star system located in the constellation Circinus. It was noted as a double star by Herschel in 1835, who estimated their 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, is it located at a distance of approximately 450 light years.

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 along a position angle of 359°.

The primary star, component A, is a B-type subgiant star with a stellar classification of B5 VI. 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.