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

TL;DR

This paper improves carbon-star wind models by incorporating grain-size dependent opacities and demonstrates that grain size effects are significant in critical cases but minimal in well-developed winds.

Contribution

It introduces a method to include grain-size dependent opacities in wind models, relaxing the small particle approximation.

Findings

Grain size effects are significant in critical wind cases.

In well-developed winds, grain size effects on mass-loss and speed are minimal.

The model accounts for time-dependent dust formation and grain-size variations.

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.