Far-infrared spectroscopy of galaxies : the 158 micron C+ line and the energy balance of molecular clouds.
Abstract
Observations of the 158 microns fine-structure line of C(+) toward the nuclei of six gas-rich galaxies are presented. The observations are compared with observations of the CO J = 1-0 and H I 21 cm lines, observations of far-IR continuum emission, and observations of forbidden C II emission with the Galaxy. The forbidden C II line comes from dense, warm gas in UV-illuminated photodissociation regions at the surfaces of molecular clouds. This line is probably optically thin in all but the brightest of galactic sources. The variation of forbidden C II brightness from source to source and its ratio to the integrated infrared continuum intensity agree well with the theoretical prediction that UV absorption by dust controls the C(+) column density. The forbidden C II line is a tracer of molecular clouds, especially those near intense sources of UV radiation.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 1985
- DOI:
- 10.1086/163113
- Bibcode:
- 1985ApJ...291..755C
- Keywords:
-
- Abundance;
- Galactic Nuclei;
- Infrared Spectroscopy;
- Interstellar Matter;
- Line Spectra;
- Molecular Clouds;
- Carbon;
- Carbon Monoxide;
- Emission Spectra;
- Energy Budgets;
- Far Infrared Radiation;
- Hydrogen Clouds;
- Ionized Gases;
- Radiant Flux Density;
- Ultraviolet Radiation;
- Astrophysics