Hydrogen Hα line emission and radiative losses in the impulsive solar events

Abstract

The electron beam effect on the Hydrogen H α -line emission and the radiative losses in the impulsive solar bursts are investigated for their dependency on time after the beam onset. The flaring atmosphere is considered to be a result of the hydrodynamical response to an electron beam injection, obtained from numerical solutions of the HD equations. Under these physical conditions we solve the full non-LTE problem for the moving hydrogenic atmosphere and calculate the theoretical H α -line profiles for the 5-level model atom with continua, including the Stark effect and the residual chromospheric absorption profile. A comparison of the observed and calculated H α profiles in impulsive events shows a good agreement of the peak intensity position and wing intensities, but the computed central intensities are up to 20% higher than those observed. The total radiative losses are shown to vary strongly in time and with depth for different spectral indices of beam and at lower chromospheric level the radiative losses are very close (up to 90%) to the energy, deposited by electron beams in a pure collisional approach.