Thiols In The ISM: First Detection Of HC(O)SH And Confirmation Of C2H5SH


Cleanest and brightest lines of t-HC(O)SH detected toward G+0.693 labeled with their corresponding quantum numbers in red. The red line shows the best LTE fit to the observed spectra (represented by the black lines). The data has been smoothed up to 3 km s−1 for an optimal line visualization. The blue lines show the spectra including the emission of all the molecules searched toward G+0.693. Note that these lines are tagged with their corresponding molecular compound in pink.

The chemical compounds carrying the thiol group (-SH) have been considered essential in recent prebiotic studies regarding the polymerization of amino acids.

We have searched for this kind of compounds toward the Galactic Centre quiescent cloud G+0.693-0.027. We report the first detection in the interstellar space of the trans-isomer of monothioformic acid (t-HC(O)SH) with an abundance of ∼1×10−10. Additionally, we provide a solid confirmation of the gauche isomer of ethyl mercaptan (g-C2H5SH) with an abundance of ∼3×10−10, and we also detect methyl mercaptan (CH3SH) with an abundance of ∼5×10−9. Abundance ratios were calculated for the three SH-bearing species and their OH-analogues, revealing similar trends between alcohols and thiols with increasing complexity.

Possible chemical routes for the interstellar synthesis of t-HC(O)SH, CH3SH and C2H5SH are discussed, as well as the relevance of these compounds in the synthesis of prebiotic proteins in the primitive Earth.

Lucas F. Rodríguez-Almeida, Izaskun Jiménez-Serra, Víctor M. Rivilla, Jesús Martín-Pintado, Shaoshan Zeng, Belén Tercero, Pablo de Vicente, Laura Colzi, Fernando Rico-Villas, Sergio Martín, Miguel A. Requena-Torres

Comments: 16 pages, 6 figures, article accepted in Astrophysical Journal Letters
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2104.08036 [astro-ph.GA] (or arXiv:2104.08036v1 [astro-ph.GA] for this version)
Submission history
From: Lucas F. Rodríguez-Almeida
[v1] Fri, 16 Apr 2021 11:14:16 UTC (284 KB)
https://arxiv.org/abs/2104.08036
Astrobiology, Astrochemistry,

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