Beta Cephei stars
Beta Cephei stars(see -fee-ÿ) (Beta Canis Majoris stars) A small group of pulsating variables, the prototypes being β Cep and β CMa. They are hot massive luminous stars of spectral types O9 to B3 with short periods of rotation (about 3–7 hours) and a very small variation in visual brightness (about 0.01–0.25 magnitudes), although the range is much greater at ultraviolet wavelengths. Some of the stars have two or even more periods of radial-velocity variation. The pulsation mechanism is still uncertain but could involve both radial and nonradial pulsations. Their position on the Hertzsprung–Russell diagram for pulsating variables is just above the main sequence, beginning at type B3.
beta Cephei stars[′bād·ə ′sef·ē‚ī ‚stärz]
A class of pulsating variables lying above the upper main sequence with short periods of 3½-6 hours, spectral classes B0 to B3, and doubly periodic light curves. Also known as beta Canis Majoris stars.