STRUCTURE AND CHEMISTRY IN THE NORTHWESTERN CONDENSATION OF THE SERPENS MOLECULAR CLOUD CORE JosEPH P. McMuLLIN AND LEE

We present single-dish and interferometric observations of gas and dust in the core of the Serpens molecular cloud, focusing on the northwestern condensation. Single-dish molecular line observations are used to probe the structure and chemistry of the condensation while high-resolution images of CS and CH 30H are combined with continuum observations from A. = 1.3 mm to A. = 3.5 em to study the subcondensations and overall distribution of dust. For the northwestern condensation, we derive a characteristic density of 3 x 105 em3 and an estimated total mass of ~ 70 M 0 . We find compact molecular emission associated with the far-infrared source S68 FIRS 1, and with a newly detected subcondensation named S68 N. Comparison of the largeand small-scale emission reveals that most of the material in the northwest condensation is not directly associated with these compact sources, suggesting a youthful age for this region. CO J = 1 --> 0 observations indicate widespread outflow activity. However, no unique association of embedded objects with outflows is possible with our observations. The SiO emission is found to be extended with the overall emission centered about S68 FIRS 1 ; the offset of the peak emission from all of the known continuum sources and the coincidence between the blueshifted SiO emission and blueshifted high-velocity gas traced by CO and CS is consistent with formation of SiO in shocks. Derived abundances of CO and HCO + are consistent with quiescent and other star-forming regions while CS, HCN, and H 2CO abundances indicate mild depletions within the condensation. Spectral energy distribution fits to S68 FIRS 1 indicate a modest luminosity (50-60 L 0 ), implying that it is a low-mass (0.5-3 M 0 ) young stellar object. Radio continuum observations of the triple source toward S68 FIRS 1 indicate that the lobe emission is varying on timescales < 1 yr while the central component is relatively constant over ~ 14 yr. The nature of a newly detected compact emission region, S68 N, is less certain due to the absence of firm continuum detections; based on its low luminosity ( < 5 L 0 ) and strong molecular emission, S68 N may be a prestellar subcondensation of gas and dust. Subject headings: ISM: clouds ISM: individual (Serpens) ISM: molecules molecular processes