Collisional line profiles of rubidium and cesium perturbed by helium and molecular hydrogen

¹ Institut d'Astrophysique de Paris, UMR 7095, CNRS, Université Pierre et Marie Curie, 98${\rm bis}$ boulevard Arago, 75014 Paris, France e-mail: allard@iap.fr
² Observatoire de Paris-Meudon, LERMA, 92195 Meudon Principal Cedex, France
³ Laboratoire de Physique Quantique, UMR 5626, CNRS, Université Paul Sabatier, 118 route de Narbonne, 31400 Toulouse, France

Received: 7 November 2005
Accepted: 29 December 2005

Abstract

Previous calculations of the far wings of the potassium and sodium doublets in a unified-line shape semi-classical theory have been used recently to improve theoretical modeling of synthetic spectra of brown dwarfs. However the comparison with observations shows missing opacity in the 0.85 to 1.1 μm range. Contributions of other alkalis such as Rb I and Cs I may resolve this problem. We present new theoretical calculations of the line profiles of these two alkalis perturbed by helium and molecular hydrogen.