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A. B. Corman, A. K. Speck (University of Missouri-Columbia)
Asymptotic Giant Branch (AGB) stars are major contributors of new elements to the cosmos. However, the nature and evolution of the dust in their circumstellar shells is not well understood. Since this dust plays a critical role in the evolution of such stars, and goes on to enrich the interstellar medium, where it is a vital ingredient in many astrophysical processes, understanding the nature and evolution of circumstellar dust is paramount. In the present study, we concentrate on carbon stars, i.e. AGB stars with their surrounding dust chemistry dominated by carbon. There have been several studies of the mid-IR spectra of carbon stars with a view to understanding the evolution of their dust. However, these studies are somewhat contradictory. We investigate the effects of various stellar and circumstellar parameters on the emerging spectrum from such stars using the 1-D radiative transfer code DUSTY. These parameters include stellar temperature, dust condensation temperature, optical depth, dust density distribution, grain size distribution and composition. By investigating these parameters we aim to understand the evolution of dust around evolved stars in terms of trends (or lack thereof) seen in observed spectral features and differentiate between competing hypothesis for the dust evolution.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.