A Linear Survey of the Mira Variable Star Instability Region of the Hertzsprung-Russell Diagram

An extensive linear pulsation study of Mira variable stars has been carried out. Approximately 100 models were calculated for 0.8, 1.0, 1.4, and 2.0 solar mass stars with effective temperatures from 2700 K to 3400 K and luminosities from 1500 to 7000 solar luminosities. All models include molecular opacities for the composition (Y, Z) = (0.28, 0.02) and a horizontal averaging of opacity in convective regions. In some models turbulent pressure was also included. From the results of this study, period-mass-radius relations have been derived for both fundamental mode and first overtone pulsation. The PMR relations have been compared to observations to see if the mode of pulsation can be identified.