期刊
ASTRONOMY & ASTROPHYSICS
卷 393, 期 3, 页码 L49-L53出版社
EDP SCIENCES S A
DOI: 10.1051/0004-6361:20021131
关键词
ISM : abundances; ISM : molecules; stars : formation; ISM : individual : IRAS 16293-2422
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: [CHD2OH] / [CH3OH] = 0 2 +/- 0 1, [CH2DOH] / [CH3OH] = 0.9 +/- 0.3, [CH3OD] / [CH3OH] = 0.04 +/- 0.02. 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 (similar to20%) 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.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据