Volume 454, Number 2, August I 2006
APEX Special Booklet
|Page(s)||L59 - L62|
|Published online||11 July 2006|
Letter to the Editor
Probable detection of H2D in the starless core Barnard 68
Leiden Observatory, PO Box 9513, 2300 RA Leiden, The Netherlands e-mail: firstname.lastname@example.org
2 INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
3 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
4 I. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany
5 Netherlands Institute for Space Research (SRON), PO Box 800, 9700 AV Groningen, The Netherlands
6 Max-Planck-Institut für Radioastromie, Auf dem Hügel 69, 53121 Bonn, Germany
7 European Southern Observatory, Karl Schwarzschild-Straße 2, 85748 Garching bei München, Germany
8 Present address: Centro Astronómico Hispano Alemán, Apt. 511, 04080 Almería, Spain
9 European Southern Observatory, Casilla 19001, Santiago 19, Chile
Accepted: 4 May 2006
Context. The presence of H2D+ in dense cloud cores underlies ion-molecule reactions that strongly enhance the deuterium fractionation of many molecular species.
Aims.We determine the H2D+ abundance in one starless core, Barnard 68, that has a particularly well established physical, chemical, and dynamical structure.
Methods.We observed the ortho-H2D+ ground-state line 110–111, the N2H+ –3 line, and the H13CO+ 4–3 line with the APEX telescope.
Results.We report the probable detection of the o-H2D+ line at an intensity K and exclusively thermal line width, and find only upper limits to the N2H+ 4–3 and H13CO+ 4–3 intensities.
Conclusions.Within the uncertainties in the chemical reaction rates and the collisional excitation rates, chemical model calculations and excitation simulations reproduce the observed intensities and that of o-H2D+ in particular.
Key words: ISM: abundances / ISM: individual objects: Barnard 68 / ISM: molecules / submillimeter
© ESO, 2006
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