WAKELAM, Valentine; CASELLI, Paola; CECCARELLI, Cecilia; HERBST, Eric; CASTETS, Alain

doi:10.1051/0004-6361:20047186

Métadonnées

Licence d’utilisation du document

WAKELAM, Valentine
Université Sciences et Technologies - Bordeaux 1 [UB]
Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux [L3AB]
Observatoire aquitain des sciences de l'univers [OASU]
Laboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]

CASELLI, Paola
INAF - Osservatorio Astrofisico di Arcetri [OAA]

CECCARELLI, Cecilia
Laboratoire d'Astrophysique de Grenoble [LAOG]

Langue

Article de revue

Ce document a été publié dans

Astronomy and Astrophysics - A&A. 2004, vol. 422, p. 159

EDP Sciences

Résumé en anglais

We report a theoretical study of sulphur chemistry, as applied to hot cores, where S-bearing molecular ratios have been previously proposed and used as chemical clocks. As in previous models, we follow the S-bearing molecular composition after the injection of grain mantle components into the gas phase. For this study, we developed a time-dependent chemical model with up-to-date reaction rate coefficients. We ran several cases, using different realistic chemical compositions for the grain mantles and for the gas prior to mantle evaporation. The modeling shows that S-bearing molecular ratios depend very critically on the gas temperature and density, the abundance of atomic oxygen, and, most importantly, on the form of sulphur injected in the gas phase, which is very poorly known. Consequently, ratios of S-bearing molecules cannot be easily used as chemical clocks. However, detailed observations and careful modeling of both physical and chemical structure can give hints on the source age and constrain the mantle composition (i.e. the form of sulphur in cold molecular clouds) and, thus, help to solve the mystery of the sulphur depletion. We analyse in detail the cases of Orion and IRAS16293-2422. The comparison of the available observations with our model suggests that the majority of sulphur released from the mantles is mainly in, or soon converted into, atomic form.< Réduire

Mots clés

abundances

molecules

star formation

Métadonnées

Licence d’utilisation du document

Resetting chemical clocks of hot cores based on S-bearing molecules

Langue

Ce document a été publié dans

Résumé en anglais

Mots clés

DOI

Origine

Unités de recherche