EDP Sciences
Free access
Issue
A&A
Volume 403, Number 2, May IV 2003
Page(s) L25 - L28
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20030297


A&A 403, L25-L28 (2003)
DOI: 10.1051/0004-6361:20030297

Letter

High NH $\mathsf{_2}$D/NH $\mathsf{_3}$ ratios in protostellar cores

J. Hatchell

Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
(Received 20 June 2002 / Accepted 1 March 2003)

Abstract
Observations of low mass protostars which probe small enough size scales to be within likely CO depletion regions show the highest [ NH 2D] /[ NH 3] ratios yet measured, of 4-33%. These molecular D/H ratios are higher than those measured on larger scales, showing that deuterium fractionation increases towards protostellar cores. As in cold clouds, such high ratios can be produced by gas-phase ion-molecule chemistry in the presence of depletion. Grain surface chemistry is less likely to explain the deuterium enhancement, as it would require higher fractionation in ices than current models predict. The link between accretion, depletion and high molecular deuterium fractionation is strongly supported.

SIMBAD Objects



© ESO 2003

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access.

An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account.
    In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.