Ro-vibrational excitation of the SO molecule by collision with the He atom

¹ LERMA and UMR 8112 of CNRS, Observatoire de Paris-Meudon, 92195 Meudon Cedex, France e-mail: [francois.lique;annie.spielfiedel]@obspm.fr
² Université du Littoral Côte d'opale, LPCA, 189A avenue Maurice Schumann, 59140 Dunkerque, France

Received: 29 May 2006
Accepted: 13 July 2006

Abstract

Context.Over the next few years, ALMA and Herschel missions will perform high spatial and spectral resolution studies at infrared and sub-millimeter wavelengths. This will provide much greater detail about the composition and evolution of molecules in space. Modeling of the spectra will require accurate radiative and collisional rates for species of astrophysical interest.

Aims.We calculate ro-vibrational excitation rate coefficients of SO by He, useful for studies of high-temperature environments.

Methods.A new accurate three dimensional (3D) potential energy surface was calculated for the SO-He system which explicitly takes into account the r-dependence of the SO vibration as well as the R-distance and θ angle which describe the relative position of the collision partners. The dynamics calculations were performed according to the VCC-IOS approximation.

Results.The new rate coefficients between the ro-vibrational levels are calculated for temperatures from 300 K to 800 K.