Pulsation and mass loss in Mira variables

A 'typical' Mira variable (one solar mass, luminosity 10,000 suns, effective temperature 2750 K, period 373 days) is proposed, and the behavior of pulsation in the outer layers of this model star is studied in the adiabatic and isothermal limits. In the adiabatic case, mass loss in the form of a steady stellar wind is produced, but the behavior of the postshock velocity does not agree well with observations, and the mass loss rate is far too large if approximate observational estimates of the photospheric density are adopted. In the isothermal case, no continuous mass loss was produced but occasional ejection of shells occurs. The time-dependence and magnitude of the emission line velocity is in reasonable agreement with observations. Behavior found in a strongly driven model might help explain the alternating high and low minima observed in RV Tauri variables and some Miras.