A type of pulsating variable, of early spectral type (O8–B6), lying just above the main sequence; abbr. BCEP. They are also known as Beta Canis Majoris stars. Magnitude variations are 0.01–0.3, with periods of 0.1–0.6 days. There is no generally accepted explanation for the variations, but both radial pulsation and non-radial pulsation appear to be involved. Beta Cephei itself varies between magnitudes 3.16 and 3.27 every 0.19 days. A short-period subgroup (BCEPS) has periods one-tenth those of the normally observed ones. See also 53 Persei Star.