%0 Journal Article
%T Hyperfine excitation of SH+ by H
%A Alexandre Zanchet
%A Fran£¿ois Lique
%A Javier R. Goicoechea
%A Niyazi Bulut
%A Octavio Roncero
%J -
%D 2020
%R 10.1051/0004-6361/202038041
%X <i>Context.<i/> SH<sup>+<sup/> is a surprisingly widespread molecular ion in diffuse interstellar clouds. There, it plays an important role by triggering the sulfur chemistry. In addition, SH<sup>+<sup/> emission lines have been detected at the UV-illuminated edges of dense molecular clouds, so-called photo-dissociation regions (PDRs), and toward high-mass protostars. An accurate determination of the SH<sup>+<sup/> abundance and of the physical conditions prevailing in these energetic environments relies on knowing the rate coefficients of inelastic collisions between SH<sup>+<sup/> molecules and hydrogen atoms, hydrogen molecules, and electrons.<i>Aims.<i/> We derive SH<sup>+<sup/>¨CH fine and hyperfine-resolved rate coefficients from recent quantum calculations for the SH<sup>+<sup/>¨CH collisions, including inelastic, exchange, and reactive processes.<i>Methods.<i/> The method we used is based on the infinite-order sudden approach.<i>Results.<i/> State-to-state rate coefficients between the first 31 fine levels and 61 hyperfine levels of SH<sup>+<sup/> were obtained for temperatures ranging from 10 to 1000 K. Fine-structure resolved rate coefficients present a strong propensity rule in favor of ¦¤<i>j<i/>£¿=£¿¦¤<i>N<i/> transitions. The ¦¤<i>j<i/>£¿=£¿¦¤<i>F<i/> propensity rule is observed for the hyperfine transitions.<i>Conclusions.<i/> The new rate coefficients will help significantly in the interpretation of SH<sup>+<sup/> spectra from PDRs and UV-irradiated shocks where the abundance of hydrogen atoms with respect to hydrogen molecules can be significant
%U https://www.aanda.org/articles/aa/full_html/2020/06/aa38041-20/aa38041-20.html