Alpha Crucis

Alpha Crucis (α Cru, α Crucis, also Acrux, HD 108248) is the brightest star in the constellation Crux, the Southern Cross, and, at a combined visual magnitude 0.77, is the twelfth brightest star in the night sky. Acrux is the southernmost first-magnitude star, just a bit more southerly than Alpha Centauri. Acrux is a multiple star system located 321 light years from the solar system. Only two components are visually distinguishable, α and α, separated by 4 arcseconds. α is magnitude 1.40 and α is magnitude 2.09, both hot class B (almost class O) stars, with surface temperatures of about 28,000 and 26,000 K respectively. Their luminosities are 25,000 and 16,000 times that of the Sun. α and α orbit over such a long period that motion is...