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Loison JC, Wakelam V, Gratier P, Hickson KM, Bacmann A, Agùndez M, Marcelino N, Cernicharo J, Guzman V, Gerin M, Goicoechea JR, Roueff E, Le Petit F, Pety J, Fuente A, Riviere-Marichalar P. Oxygen fractionation in dense molecular clouds. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 2019; 485:5777-5789. [PMID: 31427830 PMCID: PMC6699989 DOI: 10.1093/mnras/stz560] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
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.
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Affiliation(s)
- Jean-Christophe Loison
- Institut des Sciences Moléculaires (ISM), CNRS, Univ. Bordeaux, 351 cours de la Libération, 33400, Talence, France
| | - Valentine Wakelam
- Laboratoire d'astrophysique de Bordeaux, CNRS, Univ. Bordeaux, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
| | - Pierre Gratier
- Laboratoire d'astrophysique de Bordeaux, CNRS, Univ. Bordeaux, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
| | - Kevin M. Hickson
- Institut des Sciences Moléculaires (ISM), CNRS, Univ. Bordeaux, 351 cours de la Libération, 33400, Talence, France
| | - Aurore Bacmann
- Institut de Planétologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, UJF-Grenoble 1 / CNRS-INSU, 38041 Grenoble, France
| | - Marcelino Agùndez
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, 28006 Madrid, Spain
| | - Nuria Marcelino
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, 28006 Madrid, Spain
| | - José Cernicharo
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, 28006 Madrid, Spain
| | - Viviana Guzman
- Joint ALMA Observatory (JAO), Alonso de Córdova 3107, Vitacura, Santiago de Chile, Chile
| | - Maryvonne Gerin
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Ecole Normale Supérieure, F-75005 Paris, France
| | | | - Evelyne Roueff
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-92190 Meudon, France
| | - Franck Le Petit
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-92190 Meudon, France
| | - Jérome Pety
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Ecole Normale Supérieure, F-75005 Paris, France
- Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, 38406 Saint Martin d’Hyères, France
| | - Asunción Fuente
- Observatorio Astronómico Nacional (OAN, IGN), Apdo 112, E-28803 Alcalá de Henares, Spain
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