The Instability Strip for Pre–main-sequence Stars

Abstract

We investigate the pulsational properties of pre-main-sequence (PMS) stars by means of linear and nonlinear calculations. The equilibrium models were taken from models evolved from the protostellar birthline to the zero-age main sequence for masses in the range 1-4 M_solar. The nonlinear analysis allows us to define the instability strip of PMS stars in the H-R diagram. These models are used to constrain the internal structure of young stars and to test evolutionary models. We compare our results with observations of the best case of a pulsating young star, HR 5999, and we also identify possible candidates for pulsational variability among known Herbig Ae/Be stars that are located within or close to the instability strip boundaries.