Beta Cephei star
A Beta Cephei star is a pulsating variable, of spectral type O9 to B3, with a short period (3½ to 6 hours) and small magnitude range of 0.1 to 0.3 (less than those of Cepheid variables). Beta Cephei stars are confined to a narrow band of the Hertzsprung-Russell diagram near the end of core hydrogen-burning stars of roughly 10 to 20 solar masses. Most such stars expand and contract radially, but a few have odd quivering motions with complex and multiple periods that give them more random-looking light curves. The prototype is Alfirk (Beta Cephei), although members of the group are also called Beta Canis Majoris stars, after another bright example, also known by its proper name Mirzam.