Deuterium fractionation on interstellar grains studied with modified rate equations and a Monte Carlo approach

被引:79
作者
Caselli, P
Stantcheva, T
Shalabiea, O
Shematovich, VI
Herbst, E
机构
[1] Osserv Astrofis Arcetri, I-50125 Florence, Italy
[2] Ohio State Univ, Dept Phys, Columbus, OH 43210 USA
[3] Cairo Univ, Fac Sci, Dept Astron, Cairo, Egypt
[4] Russian Acad Sci, Inst Astron, Moscow 109017, Russia
[5] Ohio State Univ, Dept Phys & Astron, Columbus, OH 43210 USA
关键词
deuterium fractionation; interstellar grains; modified rate equations; Monte Carlo methods;
D O I
10.1016/S0032-0633(02)00092-2
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
The formation of singly and doubly deuterated isotopomers of formaldehyde and of singly, doubly, and multiply deuterated isotopomers of methanol on interstellar grain surfaces has been studied with a semi-empirical modified rate approach and a Monte Carlo method in the temperature range 10-20 K. Agreement between the results of the two methods is satisfactory for all major and many minor species throughout this range. If gas-phase fractionation can produce a high abundance of atomic deuterium, which then accretes onto grain surfaces, diffusive surface chemistry can produce large abundances of deuterated species, especially at low temperatures and high gas densities. Warming temperatures will then permit these surface species to evaporate into the gas, where they will remain abundant for a considerable period. We calculate that the doubly deuterated molecules CHD2OH and CH2DOD are particularly abundant and should be searched for in the gas phase of protostellar sources. For example, at 10 K and high density, these species can achieve up to 10-20% of the abundance of methanol. (C) 2002 Elsevier Science Ltd. All rights reserved.
引用
收藏
页码:1257 / 1266
页数:10
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