Structure of molecular clouds. I - Observational constraints and CO line formation
Abstract
The present status of molecular line observations is discussed. A classification of molecular clouds is suggested: type I shows little or no indication of star formation and type II has an internal H II-region. Theoretical calculations of CO-12 and CO-13 are made to show how variations in the cloud structure influence the observed quantities. The accuracy of the presently existing models derived from molecular lines is discussed and it is concluded that the uncertainties are large. The total mass is uncertain within at least a factor of 10 and quantitative determinations of the cloud structure cannot be made. Some qualitative trends of the density and the velocity field are given.
- Publication:
-
Astronomy and Astrophysics Supplement Series
- Pub Date:
- October 1980
- Bibcode:
- 1980A&AS...42...23S
- Keywords:
-
- Carbon Monoxide;
- Interstellar Gas;
- Line Spectra;
- Molecular Clouds;
- Formaldehyde;
- H Ii Regions;
- Radiative Transfer;
- Astrophysics