CEPHEID PULSATION WITH MASS LOSS EFFECTS

In order to investigate the effects of mass loss on the Cepheid pulsation, evolutionary calculations are performed for the stars of 7, 9, and 10 solar mass, respectively, with or without mass loss from the main sequence to the Cepheid strip. The pulsational properties are determined according to linear nonadiabatic radial pulsation theory. The mass-loss rates of the stars are calculated by using the empirical relation of Waldron (1984). It is found that the mass loss of the stars does not change the position of the Cepheid strip in the HR diagram and the period-radius relation of the Cepheids. A period-mass-radius relation of the Cepheids is obtained with is feasible over the instability strip.