Answers are grounded in this paper and cite their sources.
A search has been conducted for the CO(2-1) line at 230 GHz in four galaxies and it has been detected in two, IC 342 and M82. Comparison with data for the CO(1-0) line in these galaxies shows that the molecular gas in IC 342 appears to be optically thick; that in M82, however, is of low optical depth. A comparison of the gas and stellar content of the central region of M82 suggests that much of the current star formation is taking place as high-mass stars.
No takes yet. Share an insight, caveat, or question.
Knapp et al. (1980) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: