Dust driven winds of cool giant stars : dependency on grain size

Aim. In this project, theoretical models of dust driven winds of asymptotic giant branch (AGB) stars with effective temperatures within a range of 2400 − 3200 [K] and relative carbon-to-oxygen abundance C/O > 1 are studied. The aim is to understand if and how a detailed description of the grain size in winds of carbon rich AGB stars affects the wind formation and wind driving processes. Method. The computations were performed with a well tested FORTRAN code by calculating a grid of 60 models with different stellar parameters using grain size-dependent opacities. The results were then compared with models where the small particle approximation (SPA) had been used. Conclusions. The results indicate a certain dependency on grain size of the wind properties. The results from the computations of the majority of the models show no significant diferences however, especially not for the mass loss rates. Thus earlier computations performed using the SPA need not necessarily to be rejected