MARET, S.; CECCARELLI, C.; TIELENS, A. G. G. M.; CAUX, E.; LEFLOCH, B.; FAURE, A.; CASTETS, Alain; FLOWER, D. R.

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MARET, S.
Laboratoire d'Astrophysique de Grenoble [LAOG]

CECCARELLI, C.
Laboratoire d'Astrophysique de Grenoble [LAOG]

TIELENS, A. G. G. M.
SRON Netherlands Institute for Space Research [SRON]

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Article de revue

Ce document a été publié dans

Astronomy and Astrophysics - A&A. 2005, vol. 442, n° 2, p. 527-538

EDP Sciences

Résumé en anglais

We present observations of methanol lines in a sample of Class 0 low mass protostars. Using a 1-D radiative transfer model, we derive the abundances in the envelopes. In two sources of the sample, the observations can only be reproduced by the model if the methanol abundance is enhanced by about two order of magnitude in the inner hot region of the envelope. Two other sources show similar jumps, although at a lower confidence level. The observations for the other three sources are well reproduced with a constant abundance, but the presence of a jump cannot be ruled out. The observed methanol abundances in the warm gas around low mass protostars are orders of magnitude higher than gas phase chemistry models predict. Hence, in agreement with other evidences, this suggest that the high methanol abundance reflects recent evaporation of ices due to the heating by the newly formed star. The observed abundance ratios of CH3 OH, H2 CO, and CO are in good agreement with grain surface chemistry models. However, the absolute abundances are more difficult to reproduce and may point towards the presence of multiple ice components in these regions.< Réduire

Mots clés en anglais

ISM: abundances

ISM: molecules

stars: formation

Origine

Importé de hal

Unités de recherche

Laboratoire d'Astrophysique de Bordeaux (LAB) - UMR 5804