Theta Piscis Austrini

Theta Piscis Austrini, Latinized as θ Piscis Austrini, is a binary star system in the southern constellation of Piscis Austrinus. It is faintly visible to the naked eye with a combined apparent visual magnitude of +5.01. Based upon an annual parallax shift of 10.16 mas as seen from the Earth, the system is located around 320 light years from the Sun. The system is drifting further away with a radial velocity of +13 km/s.

The binary nature of this system was discovered in 1951 by South African astronomer W. S. Finsen. Both components A and B have the same apparent magnitude. They orbit each other with a period of 20 years and an eccentricity of 0.256. The pair are A-type main sequence stars with stellar classifications of A1 V. A magnitude 11.3 visual companion star, labelled component C, is located at an angular separation of 33.2 arc seconds along a position angle of 342°, as of 1999.

Theta Piscis Austrini is moving through the Galaxy at a speed of 21.3 km/s relative to the Sun. Its projected Galactic orbit carries it between 6938 pc and 11783 pc from the center of the Galaxy. Theta Piscis Austrini came closest to the Sun 2.7 million years ago at a distance of 78.62 pc.

Naming
In Chinese, 天錢 (Tiān Qián), meaning Celestial Money, refers to an asterism consisting of refers to an asterism consisting of θ Piscis Austrini, 13 Piscis Austrini, ι Piscis Austrini, μ Piscis Austrini and τ Piscis Austrini. Consequently, the Chinese name for θ Piscis Austrini itself is 天錢二 (Tiān Qián èr, the Second Star of Celestial Money.)