The energetics of molecular clouds. I. Methods of analysis and application to the S255 molecular cloud.
Abstract
Observations of the S255 molecular cloud in the radio lines of CO, (C-13)O, and H2O as well as in the IR region from 12 to 20 microns are presented. These results show that an extended molecular cloud is associated with the optically visible H II regions S255 - S257, both the kinetic temperature and molecular density are enhanced in an area centered on a compact near-IR source, this source is also coincident with an OH and an H2O maser (within the errors), and the IR source exhibits the silicon absorption feature. First-order techniques which allow physical properties of molecular clouds to be estimated and the energetics of the gas and dust in the clouds to be analyzed are developed and applied to S255. It is concluded that: (1) the gas cooling rate is much less than the dust cooling rate; (2) the primary energy flow is in the IR through dust emission over a range of temperatures; (3) the near-IR source is apparently responsible for the local peak in gas kinetic temperature; and (4) the exciting stars of nearby H II regions appear to be the primary heat sources for the overall molecular cloud.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1977
- DOI:
- 10.1086/155594
- Bibcode:
- 1977ApJ...217..448E
- Keywords:
-
- Carbon Monoxide;
- Infrared Astronomy;
- Interstellar Gas;
- Nebulae;
- Radio Sources (Astronomy);
- Astronomical Maps;
- Cosmic Dust;
- Formaldehyde;
- H Ii Regions;
- Hydrogen;
- Infrared Spectra;
- Line Spectra;
- Molecular Spectra;
- Thermodynamic Properties;
- Astrophysics