Pulsation Theory

This review will concentrate on the question of pulsation in what we will call the Cepheid instability strip in the H-R diagram or in the log g-log T_0 diagram. This strip includes, of course, the classical δ Cephei variables, the Population II Cepheids, and the RR Lyrae variables. In addition to these, it appears that the RV Tauri variables, δ Scuti variables, and dwarf Cepheids all belong in this same general class. Clearly excluded from this class are the β Cephei variables, the Mira variables, and other types of red variables. For a more extensive discussion, the review of Ledoux & Walraven (1) is recommended.