Avior

Avior (also known as Epsilon Carinae) is a binary star system located in the southern constellation of Carina. It has an apparent magnitude of +1.86 making it the 41st brightest star in the night sky, but it is not visible from most of the northern hemisphere. The False Cross is an asterism formed of Delta Velorum, Kappa Velorum, Aspidiske (Iota Carinae) and Avior (Epsilon Carinae). It is called the False Cross because it is sometimes mistaken for the Southern Cross, causing problems in astronavigation.

Avior is located about 560–660 light years from the Sun. Measurements during the Hipparcos mission give the pair an angular separation of 0.46 arcseconds with a difference in magnitude of 2.0. At their estimated distance, this angle is equal to a physical separation of around 4 astronomical units

The main star has an apparent magnitude of 2.01, which by itself would still make it the third-brightest star in the constellation. It is an evolved giant star with a stellar classification of K3 III. However, examination of the ultraviolet light emitted from this star suggests it may instead be of spectral type K7. The fainter secondary star has an apparent magnitude of 3.85, which, if it were a single star, would be bright enough to be seen with the naked eye. This is a hot, core hydrogen-fusing B-type main sequence star of spectral class B2 Vp. The secondary star may itself have an orbiting stellar companion of spectral class F8. This pair may form an eclipsing binary system with a period of 785 days (2.15 years), resulting in a magnitude change of 0.12 during each eclipse.. See: VizieR V/50

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Category:Binary stars