Abstract
We study the time evolution of a layer of the middle or lower chromosphere being heated by a stream of energetic particles during a solar flare. The region, which is not in LTE, is allowed to cool by the transfer of Lyman continuum radiation, with collisional as well as radiative processes being considered. The resulting time dependence of the electron density and the effective thickness of the layer are in good agreement with values derived from observations. We assume the supply of energetic particles to be cut off when the central electron density of our model layer reaches the peak value of n e = 4.4 × 1013 cm−3 derived from observations of an importance 3 flare. Depending on the total hydrogen density assumed, the central electron temperature reaches a value ranging from 8000 to 10000 K. These quantities decrease by 20% during the following minute and at a slower rate thereafter.
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Kandel, R.S., Papagiannis, M.D. & Strauss, F.M. The transfer of Lyman continuum radiation in chromospheric flares. Sol Phys 21, 176–187 (1971). https://doi.org/10.1007/BF00155788
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DOI: https://doi.org/10.1007/BF00155788