期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 453, 期 1, 页码 L31-L35出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnrasl/slv094
关键词
ISM: abundances; ISM: molecules
资金
- COST Action [CM 1401]
- Universite Grenoble Alpes
- Observatoire de Grenoble
- European Research Council under the European Union's Seventh Framework Programme (FP) [320951]
New insights into the formation of interstellar formamide, a species of great relevance in prebiotic chemistry, are provided by electronic structure and kinetic calculations for the reaction NH2 + H2CO -> NH2CHO + H. Contrarily to what previously suggested, this reaction is essentially barrierless and can, therefore, occur under the low temperature conditions of intestellar objects thus providing a facile formation route of formamide. The rate coefficient parameters for the reaction channel leading to NH2CHO + H have been calculated to bA = 2.6 x 10(-12) cm(3) s(-1), beta = -2.1 and gamma = 26.9 K in the range of temperatures 10-300 K. Including these new kinetic data in a refined astrochemical model, we show that the proposed mechanism can well reproduce the abundances of formamide observed in two very different interstellar objects: the cold envelope of the Sun-like protostar IRAS16293-2422 and the molecular shock L1157-B2. Therefore, the major conclusion of this Letter is that there is no need to invoke grain-surface chemistry to explain the presence of formamide provided that its precursors, NH2 and H2CO, are available in the gas phase.
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