Dust formation in oxygen-rich circumstellar shells around long-period variables

K.S. Jeong, J.M. Winters, and E. Sedlmayr

Contributed talk presented at the IAU Symposium 191: AGB Stars, August 27th - September 1st 1998, Montpellier, France

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Abstract:

We present the first steps of our work aimed at a consistent time-dependent modeling of oxygen-rich circumstellar dust shells (CDS) around pulsating AGB stars. The nature of the most likely nucleation seeds is investigated for this situation and we find that TiO2 is a most promising candidate to serve as the primary condensate, forming already at temperatures well above 1000 K. These nuclei evolve to macroscopic dust grains by heterogeneous growth processes involving several chemical species. We investigate the varying chemical composition of the resulting dust grains as they evolve as a function of time in a fluid element moving through the CDS of an oxygen-rich long-period variable star (LPV).