MOLECULAR GAS IN THE EARLY-TYPE STARBURST GALAXY NGC 3928

Observations of (CO)-C-12 J = 1 --> 0, 2 --> 1, 3 --> 2 and (CO)-C-13 J = 1 --> 0 emission in the SO/a galaxy NGC 3928, which is believed to be undergoing nuclear starburst, are reported. The line ratios are co nsistent with optically thick (CO)-C-12 lines with molecular gas at le ast as warm as that in the Galactic disk. The physical conditions of t he molecular gas in NGC 3928 are likely comparable to the molecular ga s in the nuclear regions of spiral galaxies. The molecular gas is conf ined to an 11'' (0.9 kpc) disk with an average surface density of 400 M./pc2 and is clearly associated with the miniature spiral disk, which may have been captured by an otherwise gas-poor elliptical galaxy.