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Rachel Friesen - NRAO/University of Victoria

Wednesday, May 27 – 7:45-8:30PM


“Clustered Low Mass Star Formation in the Ophiuchus Molecular Cloud”


Dense cores within molecular clouds are the formation sites of stars and small stellar clusters. Due to the depletion of CO, nitrogen-based or deuterated molecules and molecular ions are expected to be the best tracers of the physical conditions within dense cores. Observations of these species across dense cores are needed to understand better the gas chemistry in more complex environments. For example, recent observations and chemical models suggest the relative abundances of NH3 and N2H+ vary as a function of core evolutionary status.

In this detailed study, I will present GBT and interferometer observations of NH3 emission in three dense, fragmented cores in the cluster-forming Ophiuchus molecular cloud, and compare the distribution of NH3 with that of N2H+. Unlike in isolated starless cores, we find significant offsets between the thermal dust continuum and NH3 and N2H+ emission, and observe decreasing abundance trends with increasing H2 column density in both species. We attribute these discrepancies to abundance effects, which may be due to depletion in the densest core regions. Substantial heavy molecule depletion in dense cores is expected to lead to the increased abundance of deuterated species. I will additionally show the first results of H2D+ mapping across the Oph B2 core to study the deuteration chemistry in a cluster-forming core.


Related Reference(s):

Friesen et al., ApJ, In Press, Astro-ph: 0903.0690 (2009).

Di Francesco et al., Protostars and Planets V Proceedings (2007).