van Dishoeck, E. F. and Phillips, T. G. and Keene, J. and Blake, G. A. (1992) Ground-based searches for interstellar H_(2)D^+. Astronomy and Astrophysics, 261 (1). L13-L16. ISSN 0004-6361 http://resolver.caltech.edu/CaltechAUTHORS:20120919-115851027
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We present ground-based searches for the 1_(10) - 1_(11) line of interstellar H_(2)D^(+) at 372 GHz which are more sensitive than those obtained from the Kuiper Airborne Observatory by factors of 3-4 for extended sources and by more than two orders of magnitude for compact sources. The line was not detected in a variety of interstellar clouds, including NGC 2264 toward which a possible detection had been suggested previously. The inferred H_(2)D^(+) abundance limits of 10^(-10) - 10^(-11) are still consistent with, but approach the abundances predicted by chemical models. Simultaneous observations of the DCO^(+) 3-2 and N_(2)H^(+) 4-3 lines have been used to place additional limits on the H_(3)^(+) abundance, and suggest 10^(-11) < x(H_(3)^(+))< 10^(-9). The N_(2)H^(+) data also indicate that for NGC 2264, but perhaps not for the other sources, gas-phase N_2 contains a substantial fraction of the available nitrogen in the cloud.
|Additional Information:||© 1992 EDP Sciences. Received April 24, accepted May 15, 1992. The authors are grateful to the CSO staff for their support, and to J. Black and J. Rawlings for discussions. Financial backing came from NSF grant AST 90-15755 and the Netherlands Organization for Scientific Research, NWO.|
|Subject Keywords:||Interstellar molecules: H2D+; Molecular Clouds|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||19 Sep 2012 21:21|
|Last Modified:||26 Dec 2012 16:13|
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