41 G. Arae

41 G. Arae, also known as Gliese 666, is a trinary 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 and not the Flamsteed designation. The combined apparent magnitude is +5.48, making it faintly visible to the naked eye in locations far from light pollution. This system lies at a distance of and thus is relatively nearby.

Characteristics

41 G. Arae is a hierarchical triple star system, made up of an outer pair, 41 G. Arae A and B, and an inner pair, 41 G. Arae Ba and Bb. Two other visual companions were proposed, but neither share the system's motion. 41 G. Arae A and B share a highly eccentric orbit that takes around a millennium to complete. Their semi-major axis is of 112 astronomical units., the last periastron was in 1908.
The primary star in this system is a G-type main sequence star with a stellar classification of G8V. It has about 87% of the mass of the Sun, and 82% of the Sun's radius.
The secondary component of the outer binary, 41 G. Arae B, is itself a pair of red dwarfs that complete an orbit around each other every 88 days, and are also in an eccentric orbit. Their semi-major axis is of 0.36 astronomical units. 41 G. Arae Ba and Bb have masses of 0.60 and 0.41 solar masses, respectively. It has a peculiar spectrum that shows a deficiency in elements with a higher atomic number than helium.

This system has a relatively high proper motion, moving over a second of arc across the sky each year. The space velocity components of this system are =. The stars in this system show low chromospheric activity, and have a net space velocity of 52 km/s relative to the Sun. This, in combination with their low metallicity, shows that the pair belongs to the old disk population.