First Observations of the CO J = 6--5 Transition in Starburst Galaxies
Abstract
We report the detection of carbon monoxide (CO) J = 6-5 emission from the starburst nuclei of the galaxies NGC 253, M82, and IC 342. We have used the 6-5 transition as a thermometer of warm molecular gas in starburst nuclei, unambiguously finding that the nuclear molecular gas in starburst galaxies is substantially warmer than in typical disk clouds. Nuclear-as heating could be either large scale, for example, turbulent motions or cloud-cloud collisions in noncircular bar orbits; more local effects of radiation from high-mass star formation and supernovae; or some combination. High CO excitation temperatures can affect galactic nuclear mass estimates and consequently star formation efficiencies deduced from lower J CO lines.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 1991
- DOI:
- 10.1086/186216
- Bibcode:
- 1991ApJ...382L..75H
- Keywords:
-
- Carbon Monoxide;
- Galactic Nuclei;
- Interstellar Gas;
- Molecular Spectra;
- Starburst Galaxies;
- Submillimeter Waves;
- Molecular Clouds;
- Rotational Spectra;
- Star Formation Rate;
- Astrophysics;
- GALAXIES: INDIVIDUAL ALPHANUMERIC: IC 342;
- GALAXIES: INDIVIDUAL MESSIER NUMBER: M82;
- GALAXIES: INDIVIDUAL NGC NUMBER: NGC 253;
- GALAXIES: INDIVIDUAL NGC NUMBER: NGC 6946;
- GALAXIES: INTERSTELLAR MATTER;
- STARS: FORMATION