A comparison of laboratory spectra with a new theoretical study of potassium resonance lines perturbed by helium

¹ Department of Physics and Astronomy, University of Louisville, Louisville, KY 40292, USA
² GEPI, Observatoire de Paris, 61 avenue de l’Observatoire, 75014 Paris, France
³ Institut d’Astrophysique de Paris, UMR 7095, CNRS, Université Paris VI, 75014 Paris, France
⁴ TAMP, Harvard-Smithsonian Center for Astrophysics, 60 Garden Sreet, Cambridge, Massachusetts 02138, USA

Abstract

The optical spectra of L- and T-type dwarfs exhibit a continuum dominated by the far wings of the absorption profiles of the Na 3s-3p and K 4s-4p doublets perturbed by molecular hydrogen and helium. We examine the K resonance line wing and core with a unified line profile theory and compare to laboratory experiments and observations of the cool brown dwarf ϵ Indi Ba,b.