WAKELAM, Valentine; VASTEL, C.; AIKAWA, Y.; COUTENS, A.; BOTTINELLI, S.; CAUX, E.

doi:10.1093/mnras/stu1920

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WAKELAM, Valentine
Laboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]
Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux [L3AB]
Observatoire aquitain des sciences de l'univers [OASU]
Université de Bordeaux [UB]
AMOR 2014

VASTEL, C.
Centre d'étude spatiale des rayonnements [CESR]
Centre d'étude spatiale des rayonnements [CESR]

AIKAWA, Y.

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Monthly Notices of the Royal Astronomical Society. 2014, vol. 445, n° 3, p. 2854-2871

Oxford University Press (OUP): Policy P - Oxford Open Option A

Résumé en anglais

IRAS 16293-2422 is a well studied low-mass protostar characterized by a strong level of deuterium fractionation. In the line of sight of the protostellar envelope, an additional absorption layer, rich in singly and doubly deuterated water has been discovered by a detailed multiline analysis of HDO. To model the chemistry in this source, the gas-grain chemical code Nautilus has been used with an extended deuterium network. For the protostellar envelope, we solve the chemical reaction network in infalling fluid parcels in a protostellar core model. For the foreground cloud, we explored several physical conditions (density, cosmic ionization rate, C/O ratio). The main results of the paper are that gas-phase abundances of H2O, HDO and D2O observed in the inner regions of IRAS16293-2422 are lower than those predicted by a 1D dynamical/chemical (hot corino) model in which the ices are fully evaporated. The abundance in the outer part of the envelope present chaotic profiles due to adsorption/evaporation competition, very different from the constant abundance assumed for the analysis of the observations. We also found that the large abundances of gas-phase H2O, HDO and D2O observed in the absorption layer are more likely explained by exothermic surface reactions rather than photodesorption processes.< Réduire

Mots clés en anglais

Astrochemistry

stars: protostars

ISM: abundances

ISM: molecules

ISM: IRAS16293-2422

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Chemical modelling of water deuteration in IRAS16293-2422

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