Bulut, N., Roncero, O., Aguado, A., Loison, J-C, Navarro-Almaida, D., Wakelam, V, Fuente, A., Roueff, E., Le Gal, R., Caselli, P., Gerin, M., Hickson, K. M., Spezzano, S., Riviere-Marichalar, P., Alonso-Albi, T., Bachiller, R., Jimenez-Serra, I, Kramer, C., Tercero, B., Rodriguez-Baras, M., Garcia-Burillo, S., Goicoechea, J. R., Trevino-Morales, S. P., Esplugues, G., Cazaux, S., Commercon, B., Laas, J., Kirk, J., Lattanzi, V, Martin-Domenech, R., Munoz-Caro, G., Pineda, J., Ward-Thompson, D., Tafalla, M., Marcelino, N., Malinen, J., Friesen, R., Giuliano, B. M., Agundez, M. and Hacar, A. (2021). Gas phase Elemental abundances in Molecular cloudS (GEMS): III. Unlocking the CS chemistry: the CS plus O reaction. Astron. Astrophys., 646. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

Context. Carbon monosulphide (CS) is among the most abundant gas-phase S-bearing molecules in cold dark molecular clouds. It is easily observable with several transitions in the millimeter wavelength range, and has been widely used as a tracer of the gas density in the interstellar medium in our Galaxy and external galaxies. However, chemical models fail to account for the observed CS abundances when assuming the cosmic value for the elemental abundance of sulfur. Aims. The CS+O -> CO + S reaction has been proposed as a relevant CS destruction mechanism at low temperatures, and could explain the discrepancy between models and observations. Its reaction rate has been experimentally measured at temperatures of 150-400 K, but the extrapolation to lower temperatures is doubtful. Our goal is to calculate the CS+O reaction rate at temperatures <150 K which are prevailing in the interstellar medium. Methods. We performed ab initio calculations to obtain the three lowest potential energy surfaces (PES) of the CS+O system. These PESs are used to study the reaction dynamics, using several methods (classical, quantum, and semiclassical) to eventually calculate the CS + O thermal reaction rates. In order to check the accuracy of our calculations, we compare the results of our theoretical calculations for T similar to 150-400 K with those obtained in the laboratory. Results. Our detailed theoretical study on the CS+O reaction, which is in agreement with the experimental data obtained at 150-400 K, demonstrates the reliability of our approach. After a careful analysis at lower temperatures, we find that the rate constant at 10 K is negligible, below 10(-15) cm(3) s(-1), which is consistent with the extrapolation of experimental data using the Arrhenius expression. Conclusions. We use the updated chemical network to model the sulfur chemistry in Taurus Molecular Cloud 1 (TMC 1) based on molecular abundances determined from Gas phase Elemental abundances in Molecular CloudS (GEMS) project observations. In our model, we take into account the expected decrease of the cosmic ray ionization rate, zeta(H2), along the cloud. The abundance of CS is still overestimated when assuming the cosmic value for the sulfur abundance.

Item Type: Journal Article
Creators:
CreatorsEmailORCIDORCID Put Code
Bulut, N.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Roncero, O.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Aguado, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Loison, J-CUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Navarro-Almaida, D.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Wakelam, VUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Fuente, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Roueff, E.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Le Gal, R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Caselli, P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Gerin, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Hickson, K. M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Spezzano, S.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Riviere-Marichalar, P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Alonso-Albi, T.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Bachiller, R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Jimenez-Serra, IUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Kramer, C.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Tercero, B.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Rodriguez-Baras, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Garcia-Burillo, S.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Goicoechea, J. R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Trevino-Morales, S. P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Esplugues, G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Cazaux, S.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Commercon, B.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Laas, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Kirk, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Lattanzi, VUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Martin-Domenech, R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Munoz-Caro, G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Pineda, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Ward-Thompson, D.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Tafalla, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Marcelino, N.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Malinen, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Friesen, R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Giuliano, B. M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Agundez, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Hacar, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
URN: urn:nbn:de:hbz:38-605849
DOI: 10.1051/0004-6361/202039611
Journal or Publication Title: Astron. Astrophys.
Volume: 646
Date: 2021
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:
KeywordsLanguage
POTENTIAL-ENERGY SURFACE; DISSOCIATIVE RECOMBINATION; SULFUR CHEMISTRY; CARBON MONOSULFIDE; RATE COEFFICIENTS; DYNAMICS THEORY; STAR-FORMATION; RATE-CONSTANT; CORES; IONIZATIONMultiple languages
Astronomy & AstrophysicsMultiple languages
URI: http://kups.ub.uni-koeln.de/id/eprint/60584

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