Abstract
We study the effect of chromospheric bombardment by an electron beam during solar flares. Using a semi-empirical flare model, we investigate energy balance at temperature minimum level and in the upper photosphere. We show that non-thermal hydrogen ionization (i.e., due to the electrons of the beam) leads to an increase of chromospheric hydrogen continuum emission, H− population, and absorption of photospheric and chromospheric continuum radiation. So, the upper photosphere is radiatively heated by chromospheric continuum radiation produced by the beam. The effect of hydrogen ionization is an enhanced white-light emission both at chromospheric and photospheric level, due to Paschen and H− continua emission, respectively. We then obtain white-light contrasts compatible with observations, obviously showing the link between white-light flares and atmospheric bombardment by electron beams.
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Aboudarham, J., Henoux, J.C. Electron beam as origin of white-light solar flares. Sol Phys 121, 19–30 (1989). https://doi.org/10.1007/BF00161685
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DOI: https://doi.org/10.1007/BF00161685