Oxygen fractionation in dense molecular clouds
Abstract
We have developed the first gas-grain chemical model for oxygen fractionation (also including sulphur fractionation) in dense molecular clouds, demonstrating that gas-phase chemistry generates variable oxygen fractionation levels, with a particularly strong effect for NO, SO, O2, and SO2. This large effect is due to the efficiency of the neutral 18O + NO, 18O + SO, and 18O + O2 exchange reactions. The modeling results were compared to new and existing observed isotopic ratios in a selection of cold cores. The good agreement between model and observations requires that the gas-phase abundance of neutral oxygen atoms is large in the observed regions. The S16O/S18O ratio is predicted to vary substantially over time showing that it can be used as a sensitive chemical proxy for matter evolution in dense molecular clouds.
Cite
@article{arxiv.1902.08840,
title = {Oxygen fractionation in dense molecular clouds},
author = {Jean-Christophe Loison and Valentine Wakelam and Pierre Gratier and Kevin M. Hickson and Aurore Bacmann and Marcelino Agùndez and Nuria Marcelino and José Cernicharo and Viviana Guzman and Maryvonne Gerin and Javier R. Goicoechea and Evelyne Roueff and Franck Le Petit and Jérome Pety and Asunción Fuente and Pablo Riviere-Marichalar},
journal= {arXiv preprint arXiv:1902.08840},
year = {2019}
}
Comments
22 pages, 5 figures