Volume 393, Number 3, October III 2002
|Page(s)||L49 - L53|
|Published online||01 October 2002|
Letter to the Editor
Detection of doubly-deuterated methanol in the solar-type protostar IRAS 16293-2422
CESR CNRS-UPS, BP 4346, 31028 Toulouse Cedex 04, France
2 Observatoire de Bordeaux, BP 89, 33270 Floirac, France
3 Laboratoire d'Astrophysique, Observatoire de Grenoble, BP 53, 38041 Grenoble Cedex 09, France
4 SRON, PO Box 800, 9700 AV Groningen, The Netherlands
5 Department of Physics, The Ohio State University, 174 W. 18th Ave. Columbus, OH 43210-1106, USA
6 College of Natural Sciences, Dakota State University, Madison, SD 57042-1799, USA
7 LERMA & FRE 2460 du CNRS, Observatoire de Paris, 61 Av. de l'Observatoire de Paris, 75014 Paris, France
8 Instituto de Astronomía, UNAM, Apdo Postal 72-3 (Xangari), 58089 Morelia, Michoacán, México
Corresponding author: B. Parise, Berengere.Parise@cesr.fr
Accepted: 2 August 2002
We report the first detection of doubly-deuterated methanol (CHD2OH), as well as firm detections of the two singly-deuterated isotopomers of methanol (CH2DOH and CH3OD), towards the solar-type protostar IRAS 16293-2422. From the present multifrequency observations, we derive the following abundance ratios: , , . The total abundance of the deuterated forms of methanol is greater than that of its normal hydrogenated counterpart in the circumstellar material of IRAS 16293-2422, a circumstance not previously encountered. Formaldehyde, which is thought to be the chemical precursor of methanol, possesses a much lower fraction of deuterated isotopomers (~20%) with respect to the main isotopic form in IRAS 16293-2422. The observed fractionation of methanol and formaldehyde provides a severe challenge to both gas-phase and grain-surface models of deuteration. Two examples of the latter model are roughly in agreement with our observations of CHD2OH and CH2DOH if the accreting gas has a large (0.2–0.3) atomic D/H ratio. However, no gas-phase model predicts such a high atomic D/H ratio, and hence some key ingredient seems to be missing.
Key words: ISM: abundances / ISM: molecules / stars: formation / ISM: individual: IRAS 16293-2422
© ESO, 2002
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.