DUST FORMATION IN WINDS OF LONG-PERIOD VARIABLES .4. ATMOSPHERIC DYNAMICS AND MASS-LOSS

We have calculated radiation-hydrodynamical model of the atmosphere an d circumstellar dust shell of C-rich long-period variables which inclu de a detailed description of the dust formation process. We discuss th e time-dependent behaviour of the circumstellar envelope (e.g. multipe riodicity) and its relevance for observational properties like near-IR light curves and investigate the time-averaged mass loss characterist ics of a sample of models satisfying radius-luminosity-mass and period -luminosity relations. The results can be summarized as follows: The d ependence of the mass loss rate on stellar parameters predicts a stron g increase of mass loss as stars evolve along the AGE. The models pres ented agree reasonably well with mean mass loss-period relations deduc ed from observations of Mira stars and the observed scatter of mass lo ss rates for a given period can be understood in terms of pulsation am plitude or nonlinearities of the wind mechanism. The wind velocities s how a good correlation with the quantity (rho(d)/rho(g)) L(star)/M(sta r) which characterizes the strength of radiation pressure on dust rela tive to gravitation.