2 Andromedae
Binary star system in the constellation Andromeda / From Wikipedia, the free encyclopedia
2 Andromedae, abbreviated 2 And, is a binary star[4] system in the northern constellation of Andromeda. 2 Andromedae is the Flamsteed designation. It is a faint star system but visible to the naked eye with a combined apparent visual magnitude of 5.09.[3] Based upon an annual parallax shift of 7.7 mas,[2] it is located 420 light years away. The binary nature of the star was discovered by American astronomer Sherburne Wesley Burnham at Lick Observatory in 1889.[12] The pair orbit each other over a period of 74 years with a high eccentricity of 0.8.[4]
The magnitude 5.26[4] primary, designated component A, is an A-type main-sequence star based on a stellar classification of A1V[5] or A2V,[4] although it may have already left the main sequence.[8] It was identified as a candidate Lambda Boötis star, but this was ruled out by Paunzen et al. (2003) as it doesn't match the typical characteristics of these objects.[13] Although 2 And does not display a significant infrared excess, it is a shell star that displays varying absorption features due to circumstellar dust grains. This may indicate it has an orbiting debris disk containing gas that is being viewed edge-on.[14] The star is about 100 million years old and is spinning rapidly with a projected rotational velocity of 212 km/s.[9]
The magnitude 7.43[4] secondary companion, component B, is a suspected variable star and may be a Delta Scuti variable.[4] Alternatively, it may be an ellipsoidal variable with a brown dwarf companion.[8] It is an F-type main-sequence star with a class of F1V/F4.[4]