Deuterium fractionation in warm dense interstellar clumps

Roueff, E., Parise, Berengere and Herbst, E. 2007. Deuterium fractionation in warm dense interstellar clumps. Astronomy and Astrophysics 464 (1) , pp. 245-252. 10.1051/0004-6361:20066531

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Abstract

Aims.In a recently published 1-millimeter line survey of the Orion Bar by Leurini et al., the confirmation of dense neutral clumps was reported based mainly on an analysis of methanol spectral lines. Within these clumps, a high abundance ratio was found between the deuterated isotopologue DCN and HCN. Methods.In this paper, we use steady-state chemical modelling to determine if the DCN/HCN abundance ratio can be understood in terms of gas-phase processes. Results.Our results show that, at temperatures (50-75 K) and densities ( 5 - 20 x 10{6} cm-3) in the vicinity of those measured, the calculated DCN/HCN abundance ratio can reach 0.01 or even higher, in good agreement with the measured range of 0.007-0.009. Moreover, the fractional abundance of HCN is also calculated to be in the vicinity of that reported. Other computed abundance ratios between deuterated and normal isotopologues are reported for the physical conditions of the clumps. The abundance ratios are analyzed as functions of temperature and density in terms of a simple formula. In general, calculated ratios can be somewhat dependent on the choice of two very different sets of elemental abundances, one of which is the "standard" low-metal set, while the other we term the "warm-core" set.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Subjects:	Q Science > QB Astronomy
Uncontrolled Keywords:	ISM: abundances; ISM: molecules; molecular processes
Additional Information:	Pdf uploaded in accordance with publisher's policy at http://www.sherpa.ac.uk/romeo/issn/0004-6361/ (accessed 17/04/2014)
Publisher:	EDP Sciences
ISSN:	0004-6361
Date of First Compliant Deposit:	30 March 2016
Last Modified:	20 May 2023 03:47
URI:	https://orca.cardiff.ac.uk/id/eprint/52815

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