41 G. Arae

Primary of Circe.

41 G. Arae or GJ 666 A is a binary star system in the constellation Ara. Although often called just 41 Arae, it is more accurate to call it 41 G. Arae, as the number 41 is the Gould designation (Flamsteed only covered the northern hemisphere).

The primary star in this system is a G-type main sequence star with a stellar classification of G8V. It has about 81% of the mass of the Sun, and 79% of the Sun's radius. The fainter member of the pair has a peculiar spectrum that shows a deficiency in metals, which, for astronomical purposes, are the elements heavier than Helium.

The two stars share a highly elliptical orbit that takes several centuries to complete. The estimates of the period range from 693 to 2,200 years, and the average separation of the two stars is about 210 AUs (or 210 times the average distance between the Earth and the Sun).