Effect of Lyman radiation transfer on the formation of the H-alpha line in supergiant chromospheres

Abstract

The paper pesents radiative transfer calculations of the H-alpha line in spherically expanding chromospheres of late-type supergiants where the assumption of radiative detailed balance in Lyman transitions has been relaxed. The chromospheres have been modeled as regions with outward-positive velocity and temperature gradients. Relaxation of the assumption of radiative detailed balance resulting in the escape of both Lyman continuum and line photons affects the ionization structure of hydrogen as well as the distribution of level populations in the line-forming region. The shape and strength of the new H-alpha profiles are different though the overall changes are not drastic for the densities and temperatures considered here. The implications of the new results for the chromospheres of a sample of G and K supergiants are discussed.