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Discovery of Interstellar Anions in Cepheus and AurigaWe report the detection of microwave emission lines from the hydrocarbon anion C6H(-) and its parent neutral C6H in the star-forming region LI251 A (in Cepheus), and the pre-stellar core LI512 (in Auriga). The carbon chain-bearing species C4H, HC3N, HC5N, HC7N, and C3S are also detected in large abundances. The observations of L1251A constitute the first detections of anions and long-chain polyynes and cyanopolyynes (with more than five carbon atoms) in the Cepheus Flare star-forming region, and the first detection of anions in the vicinity of a protostar outside of the Taurus molecular cloud complex, indicating a possible wider importance for anions in the chemistry of star formation. Rotational excitation temperatures have been derived from the HC3N hyperfine structure lines and are found to be 6.2 K for L1251A and 8.7 K for LI5l2. The anion-to-neutral ratios are 3.6% and 4.1%, respectively, which are within the range of values previously observed in the interstellar medium, and suggest a relative uniformity in the processes governing anion abundances in different dense interstellar clouds. This research contributes toward the growing body of evidence that carbon chain anions are relatively abundant in interstellar clouds throughout the Galaxy, but especially in the regions of relatively high density and high depletion surrounding pre-stellar cores and young, embedded protostars.
Document ID
20120013632
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Cordiner, M. A.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Charnely, S. B.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Buckle, J. V.
(Cambridge Univ. Cambridge, United Kingdom)
Walsh, C.
(Queens Univ. Belfast, United Kingdom)
Date Acquired
August 26, 2013
Publication Date
April 1, 2011
Publication Information
Publication: The Astrophysical Journal Letters
Volume: 730
Issue: 2
Subject Category
Astrophysics
Report/Patent Number
GSFC.JA.6403.2012
Distribution Limits
Public
Copyright
Other

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