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Alula Australis is also known as Xi Ursae Majoris, HR 4375, and Gl 423. Its name means "southern first spring". Nearby possible quadruple star system, consisting of two yellow dwarf stars with low mass spectroscopic companions. This was the first binary star found to be orbiting each other, found by William Herschel in 1780. Star A straddles the line between a white-yellow and a yellow dwarf star, is slightly more massive, and slightly smaller than the Sun. It is thought to be about 2 Billion years old and classified as a RS Canum Venaticorum variable type star. Star A is a spectroscopic binary, with star Ab orbiting from 0.8 to 2.6 AU, making any habitable planetary orbit unstable. Star B is another yellow dwarf star, about 90% as massive and as large as the Sun. It may be orbited by a brown dwarf or low mass red dwarf (Bb) in a torch orbit. The pair is separated from Stars A by 12.5 to 39.9 AU. A fifth orange dwarf Bc component has been suspected at 450 AU, but appears not to move with the system. A second brown dwarf (T class) in the system was found in 2012 sharing the system's motion at 4000 AU.

Alula Australis System Web Pages[]

Alula Australis System In the News[]

Distant Brown Dwarf Discovered (2012)[]

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