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Session 48 - Circumstellar Envelopes.
Display session, Tuesday, January 14
Metropolitan Ballroom,
The outflowing circumstellar envelopes (CSEs) surrounding evolved stars are known to play an important role in replenishing and reprocessing the interstellar medium (ISM). Consequently, an accurate determination of gas mass loss rates from these sources is necessary to not only quantify the rate of reprocessing of the ISM, but also to understand the local conditions that will drive the temperature and density dependent chemistry in the CSE.
Toward this end, we have constructed a detailed, self-consistent model for the gas-phase and photo-chemistry in CSEs. We include the effects of anisotropic dust UV scattering and a large chemical network on the production/destruction of CO. To compare our results with observations, we self-consistently solve the radiative transfer problem in a moving medium for both the gas and dust, including the effect of infrared pumping by dust and by a central heat source.
We compare our results to those of Knapp amp; Morris (1985), and later studies, and find that reasonable differences exist depending upon the source properties.
