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Paper: Modelling of Circumstellar H2O Line Emission from M-type AGB Stars
Volume: 378, Why Galaxies Care About AGB Stars: Their Importance as Actors and Probes
Page: 317
Authors: Maercker, M.; Schoeier, F.L.; Olofsson, H.; Bergman, P.; Justtanont, K.
Abstract: We present results of modelling circumstellar H2O line emission toward 6 M–type AGB stars. Model line intensities are fit to ISO LWS data between 43 and 197 μm. In the cases of W Hya and R Dor the ortho–H2O ground-state line at 557GHz observed with the Odin satellite is also included. An ali code is used to handle the high optical depths involved in the H2O excitation analysis. The estimated circumstellar ortho–H2O abundances span the range (0.3 – 15)×10−4, possibly indicating the importance of several competing processes such as freeze-out onto dust grains, non-equilibrium chemistry, and, more speculatively, evaporation of comets.
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