The quantum unified theory applied to the Lyman-α profile calculation

An accurate quantum calculation of the Lyman- alpha profile is given using the unified one-perturbation theory of Tran Minh and Van Regemorter (1972) and Tran Minh et al. (1975). A real 'dissection' of the electronic collisional broadening is made and the effects of the different approximations usually made in semiclassical approaches are discussed qualitatively. It is found that simple dipolar semiclassical calculations are valid not too far from the line centre but that quantum theory must be applied in the far wings. The correct average over the perturber velocities must be made for the entire profile.