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Session 20 - Molecular Clouds, Dense Cores, and Protostars.
Display session, Monday, January 15
North Banquet Hall, Convention Center
The Orion Hot Core is a dense clump of warm gas and dust thought to be illuminated externally by a source at or near the location of the infrared peak IRc2 (L\sim 10^5L_\sun). Interpretations of the dust emission and molecular line emission lead to typical Hot Core temperature and column density parameters in the range T_gas\sim T_dust=150-300\,K and N(H_2)\sim\,10^24 cm^-2 (see Genzel amp; Stutzki 1989 for a summary). We have attempted to reconcile the observations of such high temperatures and large column densities with a plausible theoretical model for the heating and radiative transfer in dense molecular cores. We have calculated the dust and gas temperatures, as well as the emergent flux, for both internally and externally illuminated cores over a range of source luminosities (10^3\le L/L_\sun\le10^7) and cloud column densities (10^22\le N(H_2)/cm^-2\le10^25). In particular, we find that it is difficult to reproduce the observational parameters for the Orion Hot Core with models of externally illuminated clouds; only internally heated cores have such large column densities heated to such high temperatures. We discuss how our study may influence the understanding of the conditions in and around the Orion Hot Core and other ``hot core'' sources (e.g. Wilner, Welch amp; Forster 1995).
