2020A&A...637A..39N


Query : 2020A&A...637A..39N

2020A&A...637A..39N - Astronomy and Astrophysics, volume 637A, 39-39 (2020/5-1)

Gas phase Elemental abundances in Molecular cloudS (GEMS). II. On the quest for the sulphur reservoir in molecular clouds: the H2S case.

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., BACHILLER R., COMMERCON B., FRIESEN R., GARCIA-BURILLO S., GOICOECHEA J.R., GIULIANO B.M., JIMENEZ-SERRA I., KIRK J.M., LATTANZI V., MALINEN J., MARCELINO N., MARTIN-DOMENECH R., MUNOZ CARO G.M., PINEDA J., TERCERO B., TREVINO-MORALES S.P., RONCERO O., HACAR A., TAFALLA M. and WARD-THOMPSON D.

Abstract (from CDS):


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 nH>2x104. 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.

Abstract Copyright: © ESO 2020

Journal keyword(s): astrochemistry - ISM: abundances - ISM: kinematics and dynamics - ISM: molecules - stars: formation - stars: low-mass

Simbad objects: 15

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Number of rows : 15
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 Barnard 1 MoC 03 33 16.3 +31 07 51           ~ 308 0
2 [HKM99] B1-b cor 03 33 20.32 +31 07 21.5           ~ 192 0
3 [HRF2005] 3 PoC 03 33 21.3 +31 07 27           ~ 71 0
4 [KJD2006] SMM J033335+31075 PoC 03 33 21.3 +31 07 28           ~ 96 0
5 NAME Perseus Cloud SFR 03 35.0 +31 13           ~ 1266 0
6 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 4096 0
7 TMC-1 NH3 PoC 04 41 18.5 +25 48 14           ~ 16 0
8 TMC-1 CP Cld 04 41 34.97 +25 38 53.2           ~ 48 1
9 TMC-1 MoC 04 41 45.9 +25 41 27           ~ 1567 0
10 LDN 1544 DNe 05 04 16.6 +25 10 48           ~ 804 0
11 NAME Orion-KL SFR 05 35 14.16 -05 22 21.5           ~ 2207 1
12 NAME Ori A MoC 05 38 -07.1           ~ 2897 0
13 NAME Horsehead Nebula DNe 05 40 59.0 -02 27 30           ~ 492 0
14 W 33a Y*O 18 14 39.56547 -17 52 02.2260           ~ 622 0
15 RAFGL 7009S HII 18 34 20.911 -05 59 42.23           ~ 206 0

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2023.02.01-20:34:20

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