Ro-vibrational excitation of CS by He

LERMA and UMR 8112 of CNRS, Observatoire de Paris-Meudon, 92195 Meudon Cedex, France e-mail: francois.lique@obspm.fr

Received: 20 September 2006
Accepted: 12 October 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. Modeling of the spectra will require accurate radiative and collisional rates for species of astrophysical interest.

Aims.The present paper focuses on the calculation of ro-vibrational excitation rate coefficients of CS by He, useful for studies of high-temperature interstellar environments.

Methods.A new accurate three dimensional (3D) potential energy surface for the CS-He system, which explicitly takes into account the r-dependence of the CS vibration, was calculated. The dynamic calculations were performed using the VCC-IOS approximation.

Results.Cross sections among the 38 first rotational levels of , and are calculated for total energies up to 10 000 cm^-1. Rate coefficients between the ro-vibrational levels are calculated for temperatures from 300 K to 1500 K.