Formation of the solar Hα profile

A series of non-LTE radiative transfer solutions for H was computed using the integrodifferential equation technique of Athay and Skumanich (1967). A model hydrogen atom consisting of three bound levels and a continuum was assumed. It was found that increasing the temperature of the chromosphere at the height of line formation decreases the central intensity of the line. The density structure of the atmosphere primarily affects the optical depth scale rather than the source function. The temperature minimum region of the atmosphere was found to be transparent to H radiation, so that the radiation in some part of the line will arise from two distinct layers of the atmosphere, one above the temperature minimum and one below it. The computed H profile was found to be highly sensitive to the assumed 2–3 collisional cross-section.