Protostars and Planets VI, Heidelberg, July 15-20, 2013

Poster 1B078

Cyanopolyynes as a probe of infall in Serpens South

Friesen, Rachel (Dunlap Institute, University of Toronto)
Medeiros, Lia (UC-Berkeley/NRAO)
Schnee, Scott (NRAO)
Bourke, Tyler (Harvard-Smithsonian CfA)
Di Francesco, James (NRC-Herzberg)
Gutermuth, Robert (UMass-Amherst)
Myers, Philip C. (Harvard-Smithsonian CfA)

Cyanopolyynes are carbon-chain molecules of the form HC2n+1N. At higher n, these molecules are among the longest and heaviest molecules found in the interstellar medium, and to date have been primarily seen toward several nearby, low-mass star forming regions, and in the atmospheres of AGB stars. We have detected bright HC7N J = 21−20 emission toward multiple locations in the Serpens South cluster-forming region using the K-Band Focal Plane Array at the Robert C. Byrd Green Bank Telescope. HC7N is seen primarily toward cold filamentary structures that have yet to form stars, largely avoiding the dense gas associated with small protostellar groups and the main central cluster of Serpens South. Toward some HC7N ‘clumps’, we find consistent variations in the line centroids relative to NH3 (1,1) emission, as well as systematic increases in the HC7N non-thermal line widths, which we argue reveal infall motions onto dense filaments within Serpens South with mass accretion rates of M ~ 2 − 5 M⊙ Myr−1. This result extends the known star-forming regions containing significant HC7N emission from typically quiescent regions, like the Taurus molecular cloud, to more complex, active environments.

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