[Previous] | [Session 45] | [Next]
C. Covatto, P. A. Aannestad (ASU)
The winds of late-type stars are driven by radiation pressure on dust. Collisions between the gas and dust result in a net gain of momentum by the gas. When a target material is bombarded by gas atoms, the gas atoms may become trapped in the material. Molecules will form and if the binding energy is low enough for the molecule to desorb at the temperature of the target, then the target material may be eroded in this fashion. This is known as chemical sputtering. If the collisions between the target material and the impinging gas atoms are energetic enough, target atoms may be removed from the surface. This process is known as nonthermal sputtering. The equations of motion for the gas and dust are integrated and the size distribution of dust grains is calculated by the method of Krüger, Woitke, and Sedlmayr (1995; A&AS 113, 593). The effect of chemical and nonthermal sputtering on the assumed grain size distribution will be discussed. This work was supported by a NASA Space Grant.