Energetics of molecular cloud. II. The S140 molecular cloud
This paper is the second in a series dealing with the energetics of molecular clouds. The techniques presented in an earlier paper are here applied to the S140 molecular cloud. This cloud is extremely interesting because it contains a single, strong near-infrared source. The infrared source appears to be very similar to the Becklin-Neugebauer object, but the simplicity of the S140 molecular cloud results in substantial advantages for the detailed study of such objects. The conclusions of the energetics analysis of this source are similar to those from the S255 cloud, except that here the near-infrared source appears to be the dominant heat source for the dust in the cloud. Predictions of the expected far-infrared flux agree well with recent observations. The molecular line data for this source are fitted by a radiative transport model for a collapsing cloud. By contraining the model to fit several lines of several molecules, the temperature and density distributions in the cloud are appraised. This in turn allows a more detailed examination of the coupling between gas and dust temperatures. Another result of the modeling is a confirmation of the effect suggested in the S255 paper: that the fractional abundances of CO and H/sub 2/CO are less in these clouds than in dark dust clouds. The cloud model is also used to obtain accurate relative abundances of /sup 13/CO, C/sup 18/O, HCN, HCO/sup +/, and N/sub 2/H/sup +/.
- Research Organization:
- Department of Astronomy and McDonald Observatory, The University of Texas at Austin
- OSTI ID:
- 5040947
- Journal Information:
- Astrophys. J.; (United States), Vol. 219:3
- Country of Publication:
- United States
- Language:
- English
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