At magnitude 2.69, Alpha Muscae is a third-magnitude star in the constellation Musca, the Fly. It is occasionally called by the Greek name Myla, meaning "fly". Since Musca is a modern constellation that is too far south to have been visible from ancient Greece, this name was given to α Mus during the modern era, in 1752, when the constellation name "Apis" was changed to "Musca Australis".
Properties and Evolution
Alpha Muscae is a hot, blue-white class B2 IV subgiant with a surface temperature of 21,900 K. It shines from a distance of 306 light years, with a luminosity of 4,520 suns, and is so hot that most of the radiation emerges in the ultraviolet (where we cannot see it). Its temperature and luminosity indicate a radius 4.7 times the Sun's, and a mass of 8 suns.
Alpha Muscae is a part of the unbound Centaurus-Crux association of O and B type stars, all of which were born from the same massive interstellar cloud. The star is roughly midway through its 32 million year hydrogen-fusing main-sequence lifetime. Like most class B stars, α Mus rotates quickly, with an equatorial spin velocity at least 114 km/sec, and a rotation period less than two days. And also like many stars in its class, Alpha Muscae is a β Cephei-type variable, pulsating in brightness by about 1% over a 2.2 hour period.
Companion
About half an arcminute away is a 13th-magnitude companion, which could easily be a line-of-sight coincidence. If the neighbor is a true companion, it has the luminosity of a K8 V dwarf, and would be separated by at least 2600 AU, taking at least 45,000 years to make a full orbit.
[Adapted from STARS by Jim Kaler, Professor Emeritus of Astronomy, University of Illinois]