Pulsating stars

Pulsating stars are a subset of the class of intrinsic variable stars. In this review the main emphasis is on purely radial pulsations of spherically symmetric, non-rotating, non-magnetic stars. After a short review of the relevant stellar time scales, the main observational data on pulsating stars are summarized, and some elements of the basic theory of pulsating stars presented. Considerable emphasis is given to the linear theory of radial pulsations. Nonlinear pulsation calculations are also reviewed. An attempt is made to assess present understanding of the causes and nature of pulsations in the various known types of pulsating stars and some important unsolved problems are summarized and discussed. A section is included concerned with applications of pulsation theory to miscellaneous kinds of objects not ordinarily thought of as pulsating stars: stars in 'quasi-hydrostatic' equilibrium, relativistic pulsation theory, white dwarfs, neutron stars, rotating stars, magnetic stars and oscillating models of the universe.