Molecular abundances in the Magellanic Clouds II.
Molecular abundances in the Magellanic Clouds
II. Deuterated species in the LMC
-
Y.-N. Chin
-
Institute of Astronomy & Astrophysics,
Academia Sinica
- P.O. Box 1-87 Nankang, 115 Taipei, Taiwan
- and
-
Radioastronomisches Institut der Universität Bonn
- Auf dem Hügel 71, D-53121 Bonn, Germany
-
C. Henkel
-
Max-Planck-Institut für Radioastronomie
- Auf dem Hügel 69, D-53121 Bonn, Germany
- T.J. Millar
-
Department of Physics,
UMIST
- PO Box 88, Manchester M60 1QD, United Kingdom
-
J.B. Whiteoak
-
Paul Wild Observatory,
Australia Telescope National Facility,
CSIRO
- Locked Bag 194, Narrabri NSW 2390, Australia
-
R. Mauersberger
-
Steward Observatory,
The University of Arizona
- Tucson,
AZ 85721, U.S.A.
Paper published in August 1996 by the Letters to Editor of
Astronomy and Astrophysics in vol. 312, pp. L33 - L36.
If you want to have a look at the complete paper please click
here (PostScript file of 760625 bytes) or
here (gzip-compressed PostScript file of 614051 bytes).
Abstract.
The first definite discoveries of extragalactic deuterium are reported.
DCO+ has been detected in three and DCN has been measured
in one star-forming region of the Large Magellanic Cloud (LMC).
While the HCO+/DCO+ abundance ratios are found to be
19 ± 3, 24 ± 4, and 67 ± 18 for N113, N44BC and N159HW,
respectively, a HCN/DCN abundance ratio of 23 ± 5 is obtained for N113.
These results are consistent with a gas temperature of
about 20 K and a D/H ratio of about 1.5 × 10-5,
consistent with that observed in the Galaxy.
If the cloud temperature is closer to 30 K,
then a D/H ratio is required to be up to an order of magnitude larger.
Because this ratio provides a lower limit to the primordial D/H ratio, it
indicates that the baryon mass density alone is unable to close the universe.
Any suggestion or comments please
e-mail to einmann@asiaa.sinica.edu.tw.
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