The early-type variables

We review the observational status of several different kinds of intrinsic variables among the early-type stars and attempt to interpret the variations in terms of our current understanding of stellar pulsation. Four distinct types of intrinsic variable can be defined: the Cep, 53 Per, Oph and Eri stars. A simple observational classification scheme, which is readily interpreted in terms of pulsation properties, is proposed. The limits of the instability strip and pulsation constants for the Cep and 53 Per stars is discussed. Problems with the interpretation of Eri stars in terms of pulsation are pointed out. The observations are consistent with rotational modulation. A problem with mode identification in Eri stars is discussed.