Query : 2020A&A...638A..72L

2020A&A...638A..72L - Astronomy and Astrophysics, volume 638A, 72-72 (2020/6-1)

Hyperfine excitation of SH+ by H.


Abstract (from CDS):

Context. SH+ is a surprisingly widespread molecular ion in diffuse interstellar clouds. There, it plays an important role by triggering the sulfur chemistry. In addition, SH+ 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+ abundance and of the physical conditions prevailing in these energetic environments relies on knowing the rate coefficients of inelastic collisions between SH+ molecules and hydrogen atoms, hydrogen molecules, and electrons.
Aims. We derive SH+-H fine and hyperfine-resolved rate coefficients from recent quantum calculations for the SH+-H collisions, including inelastic, exchange, and reactive processes.
Methods. The method we used is based on the infinite-order sudden approach.
Results. State-to-state rate coefficients between the first 31 fine levels and 61 hyperfine levels of SH+ were obtained for temperatures ranging from 10 to 1000K. Fine-structure resolved rate coefficients present a strong propensity rule in favor of Δj=ΔN transitions. The Δj=ΔF propensity rule is observed for the hyperfine transitions.
Conclusions. The new rate coefficients will help significantly in the interpretation of SH+ spectra from PDRs and UV-irradiated shocks where the abundance of hydrogen atoms with respect to hydrogen molecules can be significant.

Abstract Copyright: © F. Lique et al. 2020

Journal keyword(s): molecular data - molecular processes - radiative transfer - methods: laboratory: molecular

Simbad objects: 5

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Number of rows : 5
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
1 NAME W3 IRS 5 Y*O 02 25 40.54 +62 05 51.4           B1 335 0
2 NAME Orion Bright Bar reg 05 35 22.30 -05 24 33.0           ~ 773 0
3 NAME ORI MOL CLOUD MoC 05 56 -01.8           ~ 926 1
4 NAME Galactic Center gam 17 45 39.60213 -29 00 22.0000           ~ 12397 0
5 NAME Sgr B2 Main Rad 17 47 20.5 -28 23 06           ~ 355 1

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