Inelastic Mg+H collision data for non-LTE applications in stellar atmospheres

¹ Department of Physics and AstronomyUppsala University, Box 515, 75120 Uppsala, Sweden
e-mail: Paul.Barklem@physics.uu.se
² Department of Theoretical Physics, Herzen University, St. Petersburg 191186, Russia
³ Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Strasse 1, 85741 Garching bei München, Germany
⁴ LERMA, Observatoire de Paris, 92195 Meudon Cedex, France
⁵ Université Paris-Est, Laboratoire Modélisation et Simulation Multi-Echelle, MSME UMR 8208 CNRS, 5 Bd Descartes, 77454 Marne-la-Vallée, France

Received: 21 February 2012
Accepted: 21 March 2012

Abstract

Rate coefficients for inelastic Mg+H collisions are calculated for all transitions between the lowest seven levels and the ionic state (charge transfer), namely Mg(3s^{2 1}S, 3s3p ³P, 3s3p ¹P, 3s4s ³S, 3s4s ¹S, 3s3d ¹D, 3s4p ³P)+H(1s) and Mg⁺(3s ²S)+H⁻. The rate coefficients are based on cross-sections from full quantum scattering calculations, which are themselves based on detailed quantum chemical calculations for the MgH molecule. The data are needed for non-LTE applications in cool astrophysical environments, especially cool stellar atmospheres, and are presented for a temperature range of 500−8000 K. From consideration of the sensitivity of the cross-sections to various uncertainties in the calculations, most importantly input quantum chemical data and the numerical accuracy of the scattering calculations, a measure of the possible uncertainties in the rate coefficients is estimated.