Models for Dense Molecular Cloud Cores

Abstract

We present a detailed model for the thermal balance, chemistry, and radiative transfer within quiescent dense molecular cloud cores that contain a central protostar. Large variations in the gas temperature are expected to affect the gas-phase chemistry dramatically; with the predicted H2O abundance varying by more than a factor of 1000 within cloud cores. Based on our predicitions for the thermal and chemical structure of the cores, we have constructed self-consistent radiative transfer models to compute line strengths and profiles for transitions of various isotopomers of CO, H2O, and OI. We predict the high lying transitions of water to be in absorption, and low gain maser emission at 183 GHz. We predict the 63 micron line of OI to be in absorption against the continuum for many sources. Finally, our model can also account successfully for recent ISO observations of absorption in rovibrational transitions of water toward the source AFGL 2591.