36 Andromedae
36 Andromedae is a binary star system in the northern constellation of Andromeda, which is part of a triple star system. The designation is from the star catalogue of English astronomer John Flamsteed, first published in 1712. It is faintly visible to the naked eye with an apparent visual magnitude of 5.45. An annual parallax shift of 26.33 mas yields a distance estimate of about 124 light years. The system is moving closer to the Sun with a radial velocity of −0.8 km/s.
Characteristics
The binary nature of 36 Andromedae was discovered in 1832 by the German-Russian astronomer Wilhelm von Struve. It is a wide binary with an orbital period of 169.1 years and an eccentricity of 0.31. Their semi-major axis is of 37 astronomical units, larger than that of Neptune. As of 2016, the pair had an angular separation of 0.90 arc seconds along a position angle of 330°.The primary, component A, is a magnitude 6.12 G-type star with a stellar classification of G8 IV, while the secondary, component B, has a magnitude of 6.54 and is a K-type star of class K3 IV. Their brightness compared to their temperatures indicate they are evolving subgiant stars. However, at least one of the components is subject to flare activity, which may suggest they are instead pre-main sequence stars.
36 Andromedae makes part of a triple star system. A third star, which shares a common proper motion with the inner pair and hence is believed to form a triple system, is separated by the AB pair by 1,407". At the system's distance, this implies a projected separation of and an estimated orbital period of seven million years. It is a K-type main-sequence star with 0.68 times the mass of the Sun and an apparent magnitude of 10.92.