Universität zu Köln

Navarro-Almaida, D., Le Gal, R., Fuente, A., Riviere-Marichalar, P., Wakelam, V, Cazaux, S., Caselli, P., Laas, J. C., Alonso-Albi, T., Loison, J. C., Gerin, M., Kramer, C., Roueff, E., Bachillerl, R., Commercon, B., Friesen, R., Garcia-Burillo, S., Goicoechea, J. R., Giuliano, B. M., Jimenez-Serram, I, Kirk, J. M., Lattanzi, V, Malinen, J., Marcelino, N., Martin-Domenech, R., Caro, G. M. Munoz, Pineda, J., Tercero, B., Trevino-Morales, S. P., Roncero, O., Hacar, A., Tafalla, M. and Ward-Thompson, D. (2020). Gas phase Elemental abundances in Molecular cloudS (GEMS): II. On the quest for the sulphur reservoir in molecular clouds: the H2S case. Astron. Astrophys., 637. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

Context. Sulphur is one of the most abundant elements in the Universe. Surprisingly, sulphuretted molecules are not as abundant as expected in the interstellar medium and the identity of the main sulphur reservoir is still an open question.Aims. Our goal is to investigate the H2S chemistry in dark clouds, as this stable molecule is a potential sulphur reservoir.Methods. Using millimeter observations of CS, SO, H2S, and their isotopologues, we determine the physical conditions and H2S abundances along the cores TMC 1-C, TMC 1-CP, and Barnard 1b. The gas-grain model NAUTILUS is used to model the sulphur chemistry and explore the impact of photo-desorption and chemical desorption on the H2S abundance.Results. Our modeling shows that chemical desorption is the main source of gas-phase H2S in dark cores. The measured H2S abundance can only be fitted if we assume that the chemical desorption rate decreases by more than a factor of 10 when n(H) > 2 x 10(4). This change in the desorption rate is consistent with the formation of thick H2O and CO ice mantles on grain surfaces. The observed SO and H2S abundances are in good agreement with our predictions adopting an undepleted value of the sulphur abundance. However, the CS abundance is overestimated by a factor of 5-10. Along the three cores, atomic S is predicted to be the main sulphur reservoir.Conclusions. The gaseous H2S abundance is well reproduced, assuming undepleted sulphur abundance and chemical desorption as the main source of H2S. The behavior of the observed H2S abundance suggests a changing desorption efficiency, which would probe the snowline in these cold cores. Our model, however, highly overestimates the observed gas-phase CS abundance. Given the uncertainty in the sulphur chemistry, we can only conclude that our data are consistent with a cosmic elemental S abundance with an uncertainty of a factor of 10.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Navarro-Almaida, D. UNSPECIFIED UNSPECIFIED UNSPECIFIED Le Gal, R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Fuente, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Riviere-Marichalar, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wakelam, V UNSPECIFIED UNSPECIFIED UNSPECIFIED Cazaux, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Caselli, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Laas, J. C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Alonso-Albi, T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Loison, J. C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Gerin, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kramer, C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Roueff, E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bachillerl, R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Commercon, B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Friesen, R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Garcia-Burillo, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Goicoechea, J. R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Giuliano, B. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Jimenez-Serram, I UNSPECIFIED UNSPECIFIED UNSPECIFIED Kirk, J. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Lattanzi, V UNSPECIFIED UNSPECIFIED UNSPECIFIED Malinen, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Marcelino, N. UNSPECIFIED UNSPECIFIED UNSPECIFIED Martin-Domenech, R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Caro, G. M. Munoz UNSPECIFIED UNSPECIFIED UNSPECIFIED Pineda, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Tercero, B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Trevino-Morales, S. P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Roncero, O. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hacar, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Tafalla, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Ward-Thompson, D. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-333946
DOI:	10.1051/0004-6361/201937180
Journal or Publication Title:	Astron. Astrophys.
Volume:	637
Date:	2020
Publisher:	EDP SCIENCES S A
Place of Publication:	LES ULIS CEDEX A
ISSN:	1432-0746
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language CHEMICAL-COMPOSITION; INTERSTELLAR CLOUDS; COLD CORES; DARK CLOUD; CHEMISTRY; DESORPTION; EXCITATION; CS; PERSEUS; ICE Multiple languages Astronomy & Astrophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/33394