First detection of interstellar S2H

Fuente, Asuncion
Goicoechea, Javier,
Pety, Jérôme
Le Gal, Romane
Martín-Doménech, Rafael
Gratier, P.
Guzman, Viviana
Roueff, Evelyne
Loison, Jean Christophe
Muñoz-Caro, Guillermo M.
Wakelam, Valentine
Gerin, Maryvonne
Riviere-Marichalar, Pablo
Vidal, Thomas

Open link

Publication date

January 2017

DOI

10.3847/2041-8213/aaa01b

Publisher

American Astronomical Society

Abstract

International audienceWe present the first detection of gas phase S2H in the Horsehead, a moderately UV-irradiated nebula. This confirms the presence of doubly sulfuretted species in the interstellar medium and opens a new challenge for sulfur chemistry. The observed S2H abundance is ~5x10$^{-11}$, only a factor 4-6 lower than that of the widespread H2S molecule. H2S and S2H are efficiently formed on the UV-irradiated icy grain mantles. We performed ice irradiation experiments to determine the H2S and S2H photodesorption yields. The obtained values are ~1.2x10$^{-3}$ and <1x10$^{-5}$ molecules per incident photon for H2S and S2H, respectively. Our upper limit to the S2H photodesorption yield suggests that photo-desorption is not a competiti...