Relaxing the Small Particle Approximation for Dust-grain opacities in Carbon-star Wind Models

Abstract

We have computed wind models with time-dependent dust formation and grain-size dependent opacities, where (1) the problem is simplified by assuming a fixed dust-grain size, and where (2) the radiation pressure efficiency is approximated using grain sizes based on various means of the actual grain size distribution. It is shown that in critical cases, the effect of grain sizes can be significant. For well-developed winds, however, the effects on the mass-loss rate and the wind speed are small.

2 pages, 2 figures. To be published in the proceedings of the conference "Why Galaxies Care about AGB Stars II", held in Vienna, August 16-20, 2010; F. Kerschbaum, T. Lebzelter T. and B. Wing eds, ASP Conf. Series