Chromospheric heating by electron and proton bombardment in the solar flare of June 7, 1980

Using observations of both hard X-rays and γ-rays in the large solar flare on June 7, 1980, we infer the amount of chromospheric heating due to bombardment both by non-thermal electrons and by protons, respectively. If a thick-target model for the X-ray bremsstrahlung is adopted, then proton heating is shown to be important only in the lower chromosphere; however, if the hard X-rays are substantially thermal in origin, then proton heating may play an important or indeed dominant role in determining the structure of the entire flaring chromosphere.