Possible gas-phase formation routes of dimethyl sulfide in extraterrestrial environments
- 1Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy (gabriella.digenova@dottorandi.unipg.it, luca.mancini@unipg.it,nadia.balucani@unipg.it)
- 2Dipartimento di Ingegneria Civile ed Ambientale, Università degli Studi di Perugia, Perugia, Italy (andrea.giustini@collaboratori.unipg.it,marzio.rosi@unipg.it)
- 3Institut de Planétologie et d'Astrophysique de Grenoble, CNRS, Univ. Grenoble Alpes, Grenoble, France (cecilia.ceccarelli@univ-grenoble-alpes.fr)
The presence of dimethyl sulfide (DMS) in the atmosphere of exoplanets has been invoked as a potential biosignature since its presence atmosphere of Earth has a biological origin. Dimethylsulfoniopropionate (DMSP) is produced by phytoplankton and then degraded to form methanethiol (CH3SH) and DMS. Microbial methylation and detoxification processes can also produce DMS from hydrogen sulfide H2S.
Recently, a tentative detection of DMS on the candidate Hycean exoplanet K2-18 b was reported in the work by Madhusudhan et al. [1]. Dimethyl sulfide is also detected in the coma of comet 67P/Churyumov-Gerasimenko [2], and its isomers ethyl mercaptan, CH3CH2SH, has been detected toward Orion KL [3]. Therefore, DMS adds to the list of S-bearing molecules identified at the moment in the extraterrestrial environment.
No formation routes of extraterrestrial DMS are reported in the literature at the moment. Therefore, we have started a systematic theoretical investigation to unveil the possible formation mechanisms of DMS in the gas phase. We make use of electronic structure calculations of the relevant potential energy surfaces and kinetics calculations to derive the energy profile and rate coefficients of each proposed reaction following the same schemes that we have previously identified for the formation of the analogous O-bearing species dimethyl ether [4].
[1] Madhusudhan, Nikku, et al. "Carbon-bearing molecules in a possible hycean atmosphere." The Astrophysical Journal Letters 956.1 (2023): L13.
[2] Hänni, N., et al. "Identification and characterization of a new ensemble of cometary organic molecules." Nature Communications 13.1 (2022): 3639.
[3] Kolesniková, Lucie, et al. "Spectroscopic characterization and detection of ethyl mercaptan in orion." The Astrophysical Journal Letters 784.1 (2014): L7.
[4] Skouteris, Dimitrios, et al. "Interstellar dimethyl ether gas-phase formation: a quantum chemistry and kinetics study." Monthly Notices of the Royal Astronomical Society 482.3 (2019): 3567-3575.
How to cite: Di Genova, G., Giustini, A., Mancini, L., Rosi, M., Ceccarelli, C., and Balucani, N.: Possible gas-phase formation routes of dimethyl sulfide in extraterrestrial environments, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-435, https://doi.org/10.5194/epsc2024-435, 2024.
