The Beta Cephei variables - Current problems

Three basic problems associated with Beta Cep stars are examined: (1) the mechanism by which pulsations are maintained, (2) the type of pulsation observed (radial or nonradial, a fundamental vibration or an overtone), and (3) the evolutionary stage. Since the Beta Cep stars lie in a narrow instability strip very close to the end of core hydrogen burning, the driving mechanism probably originates in the core of the stars. A P/L/C relation is clearly present for the majority of the variables, probably corresponding to first overtone radial pulsation, but there is evidence for at least one other mode of pulsation. Finally it is suggested that the method of age determination which matches the observational and theoretical main sequences and isochrones is of questionable validity when applied to young clusters.