The puzzling detection of D_2CO in the molecular cloud L1689N
Abstract
We present new observations of the D_2CO emission towards the small cloud L1689N in the ρ Ophiuchus complex. We surveyed five positions, three being a cut across a shock site and two probing the quiescent gas of the molecular cloud. We detected D_2CO emission in the first three positions. The measured [D_2CO] /[ H2CO] is about 3%, whereas it is ≤2% in the quiescent gas. We discuss the implications of these new observations, which suggest that the bulk of the D_2CO molecules is stored in grain mantles, and removed from the cold storage by the shock at the interface between the outflowing and quiescent gas. We review the predictions of the published models proposed to explain the observed high deuteration of formaldehyde. They fall in two basic schemes: gas phase and grain surface chemistry. None of the reviewed models is able to account for the observed [D_2CO] /[H_2CO] abundance ratio. A common characteristics shared by the models is apparently that all underestimate the atomic [D]/[H] ratio in the accreting gas.
Additional Information
© 2002 ESO. Article published by EDP Sciences. Received 11 October 2001; Accepted 8 November 2001; Published online 15 January 2002. We wish to thank Paola Caselli and Tom Millar for fruitful discussions on the deuteration in their chemical models. The Caltech Submillimeter Observatory is funded by the NSF through contract AST-9980846.Attached Files
Published - aadj112.pdf
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Additional details
- Eprint ID
- 85149
- Resolver ID
- CaltechAUTHORS:20180306-155804812
- AST-9980846
- NSF
- Created
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2018-03-07Created from EPrint's datestamp field
- Updated
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2021-11-15Created from EPrint's last_modified field