Model solar chromosphere with prescribed heating

Abstract

Computed model solar chromospheres for prescribed departures from radiative equilibrium are specified in terms of the local mechanical (nonradiative) heat input. The computations are fully non-LTE and include millions of spectral lines. From the variety of models considered, the requirements on the heat input for a positive temperature gradient, dT/dh, in different layers of the chromosphere are discussed. The derived radiative cooling function for different models show that the cooling function is model-dependent. By comparing the computed models with the Vernazza, Avrett, and Loeser (1981) models, it is shown that the VAL-C model is characterized by a total heat flux 1.4 x 10 to the 7th ergs/sq cm/per sec, most of which is dissipated near the base of the temperature plateau. Half of the radiation loss is provided by Fe II, with Ca II, Mg II, and H playing important, but secondary, roles. CO molecules and H(-) are of lesser importance even near the temperature minimum, except in cases of minimal heating.