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R. Shah (NRAO/U. Virginia), J. McMullin, J. Williams, A. Wootten (NRAO)
The northern tip of the Serpens Molecular Cloud is home to a cluster of extremely young cores with remarkably varied emission properties. We observed a two field mosaic surrounding the Class 0 protostellar source, S68N, and the famous outflow source, S68FIR with the BIMA array, and recovered zero--spacing flux with the NRAO 12~Meter telescope. The BIMA array correlator was configured to observe the hyperfine transition of {\rm NH2D} at 85.926263~GHz, the J=1 arrow 0 {\rm HCO+} line at 89.188518~GHz, and the 3~mm continuum. Our objective is to understand the relative chemical and physical evolution of these sources with the ammonia deuterium fractionation as well as tracers of outflows, dense gas, cold condensations, and ion--molecule and grain chemistries. For example, we find that the deuterated ammonia traces out a faint ridge of emission east of S68N and S68FIR, potentially tracing out dense cores; breaks up into several sources surrounding the millimeter position of S68N; and is resolved out towards S68FIR. However, much of the {\rm HCO+} is found surrounding both sources in an extended envelope, showing less of the clumping, and is not found towards the extended easter ridge of deuterated ammonia emission. With ammonia data from the VLA, we discuss how ammonia deuterium fractionation varies as a function of radius from millimeter continuum peaks and demonstrate how it may constrain the relative influences of grain and ion--molecule chemistries on ammonia throughout the cloud. Furthermore, since deuterated molecules peak in cold, dense gas, we discuss how the ammonia fractionation ratio tracks the evolution of the youngest objects, possibly age-dating regions within the cluster.
R. Shah acknowledges support from a National Radio Astronomy Observatory Jansky Pre-Doctoral Fellowship.
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The author(s) of this abstract have provided an email address for comments about the abstract: rshah@nrao.edu