HIGH-RESOLUTION MOLECULAR LINE OBSERVATIONS OF THE SERPENS-NEBULA

The Serpens Molecular cloud is a nearby low / intermediate mass star f orming region that is in the final stages of forming a densely packed cluster of stars. Spectra and high angular resolution maps of the CO, (CO)-C-13, (CO)-O-18 and (CO)-O-17 J = 2 - 1 and CO J = 4 - 3 transiti ons were obtained to study the distribution of molecular gas near the cluster. These are supplemented with data on the J = 4 - 3 HCO+ line ( to probe the denser gas), and P-3(1) P-3(0) line of atomic carbon. The mass of the region is estimated to be similar to 1450 M(circle dot), implying that the star formation efficiency in the region to date has been similar to 2.5 percent. Several molecular outflows are visible in the maps; some are associated with compact objects visible in millime tre and submillimetre wave continuum maps, as well as more widespread diffuse high velocity gas that extends over much of the nebula. The ma ss and energy of material in the high velocity gas are relatively smal l, similar to 0.3 M(circle dot) and 3 x 10(45) erg s(-1), consistent w ith the characteristics of outflows seen towards low mass star-formati on regions. The directions of the overlapping outflow lobes do not how ever show a clear alignment with the cloud's large scale magnetic fiel d as has been reported towards some other regions. The gas temperature s in the central part of the molecular cloud are warmer (similar to 30 - 40 K) than typical for dark clouds, suggesting that the Serpens clu ster has interacted with, and heated this gas. Estimates of the CO iso topomeric abundance ratios from these data may be strongly affected by opacity and radiative transfer effects. In a comparison of the LTE an d LVG techniques, the disagreement between the derived column densitie s is discussed - with particular relevance to the higher rotational tr ansitions.