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A Spectral Line Study of Serpens S68 FIRS1 Region

McMullin, Joseph P. and Mundy, Lee G. and Blake, Geoffrey A. and Wilking, Bruce A. and Mangum, Jeffrey G. and Latter, William B. (2000) A Spectral Line Study of Serpens S68 FIRS1 Region. Astrophysical Journal, 536 (2). pp. 845-856. ISSN 0004-637X. doi:10.1086/308952.

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A λ = 1 mm to 3 mm study of the Serpens molecular cloud core on scales of 10' to 10" is presented, concentrating on the northwest condensation and the embedded sources, S68 FIRS1 and S68 N. We adopt temperatures of 25 K for the extended structure (several arcminute scale) and 35 K for the embedded sources. With these values, we use molecular line ratios and LVG statistical equilibrium calculations to derive physical properties in the region. We obtain densities between 0.4-1.2 × 10^6 cm^(-3) and an overall mass of 250-300 M_☉. The majority of the mass is found in extended cloud material with two peaks of 30-45 M_☉ each. Values of the molecular column densities are derived on scales of 60"-75" (condensation) and 25"-30" (embedded sources). The column densities in the condensation are typically as high as in the embedded sources, despite a factor of 4-5 in beam area, though there is some suggestion of mild depletions on smaller scales based on interferometric observations. Derived abundances for the region show similarities to both warmer cores and colder, dark cloud regions, with some values and ratios falling cleanly between this range of properties. Measurements of several deuterated species indicate enhanced abundances, suggesting the recent evaporation of grain mantles. Overall, the combined properties and measured abundances suggest an intermediate state between the extremes of dark clouds and evolved warm cores like Orion KL. In general, the Serpens NW condensation appears very similar to the IRAS 16293-2422 region, which is itself an example of a cool, low-mass star-forming region with chemical tracers characteristic of hotter, higher mass regions. Our results support the suggestion that the general chemical morphology of a region is determined more by the age of the region than by its mass.

Item Type:Article
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Blake, Geoffrey A.0000-0003-0787-1610
Additional Information:© 2000 American Astronomical Society. Received 1999 June 15; accepted 2000 January 7. We would like to thank all of the individuals whose help was essential for obtaining the observations necessary for this project, in particular, A. �� "Taco" Zalaam for help with the CSO observations and P. Hart for light-speed tuning at the 12 m. We also thank Mary Barsony, Robert Hurt, Ronak Shah, Barry Turner, and Al Wootten for interesting discussions of this region, and our anonymous referee for productive comments and questions. This work was sponsored by National Science Foundation grant AST 91-13716 and by NASA grant 01526442. G. A. B. acknowledges additional support provided by NASA (NAG 5-4383).
Group:UNSPECIFIED, Division of Geological and Planetary Sciences
Funding AgencyGrant Number
NSFAST 91-13716
NASANAG 5-4383
Subject Keywords:ISM: abundances; ISM: individual (S68); ISM: molecules; radio continuum: ISM; stars: formation
Issue or Number:2
Record Number:CaltechAUTHORS:20120914-134721712
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Official Citation:A Spectral Line Study of Serpens S68 FIRS1 Region Joseph P. McMullin et al. 2000 ApJ 536 845
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:34103
Deposited By: Ruth Sustaita
Deposited On:14 Sep 2012 21:03
Last Modified:09 Nov 2021 23:06

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