Volume 648, April 2021
|Number of page(s)||12|
|Section||Letters to the Editor|
|Published online||07 April 2021|
Letter to the Editor
TMC-1, the starless core sulfur factory: Discovery of NCS, HCCS, H2CCS, H2CCCS, and C4S and detection of C5S⋆
Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C/ Serrano 121, 28006 Madrid, Spain
2 Observatorio Astronómico Nacional (IGN), C/ Alfonso XII, 3, 28014 Madrid, Spain
3 Centro de Desarrollos Tecnológicos, Observatorio de Yebes (IGN), 19141 Yebes, Guadalajara, Spain
Accepted: 17 March 2021
We report the detection of the sulfur-bearing species NCS, HCCS, H2CCS, H2CCCS, and C4S for the first time in space. These molecules were found towards TMC-1 through the observation of several lines for each species. We also report the detection of C5S for the first time in a cold cloud through the observation of five lines in the 31–50 GHz range. The derived column densities are N(NCS) = (7.8 ± 0.6) × 1011 cm−2, N(HCCS) = (6.8 ± 0.6) × 1011 cm−2, N(H2CCS) = (7.8 ± 0.8) × 1011 cm−2, N(H2CCCS) = (3.7 ± 0.4) × 1011 cm−2, N(C4S) = (3.8 ± 0.4) × 1010 cm−2, and N(C5S) = (5.0 ± 1.0) × 1010 cm−2. The observed abundance ratio between C3S and C4S is 340, that is to say a factor of approximately one hundred larger than the corresponding value for CCS and C3S. The observational results are compared with a state-of-the-art chemical model, which is only partially successful in reproducing the observed abundances. These detections underline the need to improve chemical networks dealing with S-bearing species.
Key words: astrochemistry / ISM: molecules / ISM: individual objects: TMC-1 / line: identification / molecular data
Based on observations carried out with the Yebes 40 m telescope (projects 19A003, 20A014, and 20D023) and the Institut de Radioastronomie Millimétrique (IRAM) 30 m telescope. The 40 m radiotelescope at Yebes Observatory is operated by the Spanish Geographic Institute (IGN, Ministerio de Transportes, Movilidad y Agenda Urbana). IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).
© ESO 2021
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