Issue |
A&A
Volume 682, February 2024
|
|
---|---|---|
Article Number | A13 | |
Number of page(s) | 5 | |
Section | Atomic, molecular, and nuclear data | |
DOI | https://doi.org/10.1051/0004-6361/202348171 | |
Published online | 29 January 2024 |
Formamide synthesis in the interstellar medium catalyzed by damaged water ice
Sorbonne Université, Laboratoire de Chimie Théorique,
UMR 7616 CNRS,
75005
Paris,
France
e-mail: alexis.markovits@sorbonne-universite.fr
Received:
5
October
2023
Accepted:
10
November
2023
Context. Formamide is one of the possible precursors of life because it has a bond analogous to the peptide bond.
Aims. In this work, we examine the reaction pathways that lead from HCN or HNC and OH to formamide. Both HCN and HNC are present in the interstellar medium, while OH could be present in interstellar water ice, which under the effect of cosmic rays, partially decomposes into H and OH.
Methods. We carried out first principles calculations. We represented the solid state either by a model of clusters or by a model of slabs that takes into account periodicity. The confrontation of these two models and with the reaction in the gas phase enabled us to find reactivity trends.
Results. For HCN, the formation of the C-N bond presents an energy barrier that cannot be overcome in the interstellar medium. The presence of water ice grains does not catalyze this step. The formation of the same bond from HNC is spontaneous, even without the presence of the solid. The second step of the pathway is a transposition of H. This step requires the presence of water ice for the barrier to allow the reaction to take place in the interstellar medium. The last step is a hydrogenation of a barrier-free radical. Our work therefore concludes that the synthesis of formamide can take place in the interstellar medium through water ice, which not only catalyzes the reaction but also constitutes a reservoir of OH.
Key words: astrochemistry / methods: numerical / ISM: abundances / astrobiology
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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