LOCATIONS OF STARBURSTS IN M82

Observations with 2''.5 (38 pc) resolution of the CO (1 --> 0) emission from the starburst nucleus of M82, obtained with the Berkeley-Illinois-Maryland Association (BIMA) six-element millimeter-wave array, have revealed unresolved (< 30 pc) structure in the CO emission with very high brightness temperature (up to 34 K). The new observations have also resolved the previously identified double lobe and central peak in the integrated CO intensity into many peaks that are all due to ''velocity crowding'' of several velocity components. Most of the CO emitting gas could be located in molecular spiral arms at 125 pc and 390 pc from the nucleus. Outflow motion (similar to 230 km s(-1)) of part of the molecular gas normal to the plane is also indicated. The new observations suggest that the starbursts took place within molecular spiral arms at some distance from the nucleus. The starbursts may in fact have propagated inward. Given the substantial amount of dense molecular gas still present in the M82 starburst region, it is not clear why the starburst activity appears to have subsided.