CO Lines toward NGC 2024 and Other Star-forming Regions: A Closer Look at the Warm Gas Component
Abstract
Observations of (C-13)O J = 6 yields 5 emission from a variety of galactic star-forming regions are reported. Sources spanning a luminosity range of six orders of magnitude were observed in this transition. These observations confirm the existence of large amounts of warm, dense, quiescent molecular gas in most Galactic star-forming regions. Mid-J lines of (C-12)O are very optically thick. The lower limit to the kinetic gas temperature is around 100 K. Typical column densities in the warm gas components are as high as 10 exp 23/sq cm or higher. The molecular hydrogen densities are high enough to keep the mid-J CO level population close to thermalized. The new measurements provide further evidence that the warm, dense, quiescent gas found in star formation regions is most likely to be heated by the energetic UV radiation escaping the H II regions around young stars.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1993
- DOI:
- 10.1086/172357
- Bibcode:
- 1993ApJ...405..249G
- Keywords:
-
- Carbon Monoxide;
- Interstellar Gas;
- Line Spectra;
- Molecular Gases;
- Radio Emission;
- Star Formation;
- H Ii Regions;
- Submillimeter Waves;
- Astrophysics;
- ISM: INDIVIDUAL NGC NUMBER: NGC 2024;
- ISM: INDIVIDUAL ALPHANUMERIC: W51;
- ISM: INDIVIDUAL ALPHANUMERIC: S106;
- ISM: INDIVIDUAL MESSIER NUMBER: M17;
- RADIO LINES: ISM;
- STARS: FORMATION