Non-analytical line profiles in stellar atmospheres

Abstract

In this work, nonanalytical line profiles for both cool and hot, dense atmospheres are added to the opacity calculations of the multipurpose stellar atmosphere code PHOENIX. Their influence on model atmospheres and synthetic spectra is studied. Model atmospheres are necessary in order to calculate synthetic spectra and to derive reliable stellar parameters. For cool, dense atmospheres, i.e., of objects of spectral type similar to and lower than latetype M, vanderWaals broadening is the most important pressure broadening mechanism. The spectra of these objects below ~1 micro-meter are dominated by alkali resonance lines. The profiles of the alkali resonance lines, especially of Na ID and KI, determine mostly the pseudo continuum in this wavelength range. Up to this work, classical analytical impact approximated alkali near line wing profiles perturbed by H2, He, and HI, which are the dominant perturbing particles, have been applied. In this work, various nonanalytical alkali line profiles, including far line wing and near line wing profiles, for Na I D, Li I, KI, and Rb I are included in order to describe the strong alkali absorption features which are characteristic for latetype dwarfs. For the alkali resonance line profiles, different theoretical approaches were used describing the far and near line wings. Non analytical alkali profiles for the far and near line wings perturbed by H2 and He are provided in the unified semiclassical theory...