MODEL ATMOSPHERES OF AGB STARS - DYNAMICS, MOLECULES AND DUST

The atmospheres and circumstellar envelopes of AGE stars are character ized by complex physical phenomena like shock waves caused by stellar pulsation or formation of molecules and dust which often lead to a hea vy mass loss and have a strong influence on IR properties as observed by ISO. To allow a physical interpretation of various observations we have con structed improved dynamical model atmospheres of long-period variables. In this contribution we mainly investigate the dependence o f the atmospheric structure and its variability on stellar pulsation, molecular opacities and time-dependent dust formation. IR spectra resu lting from our models are discussed in detail by Loidl et al. (1997b) and compared to ISO-SWS spectra obtained by I-Iron et al. (1997).