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M. Moore, S. D. Doty (Denison University)
Far-infrared radiation is often used to identify sites of star-formation. An excess of 60 um emission due to warm dust grains is sometimes considered an indication of an embedded heat source, such as a star. However, very small grains (a ~ 100 angstroms) can also contribute to this emission. Due to their small size and heat capacities, they can easily reach high temperatures even when only subjected to radiatoin from sources external to the cloud. Such grains must be included in any study of star-forming regions.
We model two sources, B335 and DC 300.2-16.9, and compare the model results to observations. From these models, we find that small grains heated by only the interstellar radiation field (ISRF) can mimic the effects of an internal heat source on larger grains. This suggests that an excess of mid-infrared radiation itself does not uniquely indicate star-formation. We present this work, as well as other methods of differentiating star-forming and non star-forming clouds. We also consider the ability to constrain the source and dust properties through such studies.