The depth and the vertical extent of the energy deposition layer in a medium-class solar flare

Abstract

We analyze here variations of the position and the vertical extent of the energy deposition layer (EDL) inthe C1.6 GOES-class solar flare observed at 10:20 UT on 2012 September 10. The variations of the EDL arecontrasted with the variations of the spectra and emission intensities recorded in the H-alpha line with the very high time resolution using the MSDP spectrograph at Bialkow Observatory. The flare radiated hard X-rays (HXR) detectable up to a energy of 70 keV. A numerical model of the flare used in the analysis assumes that the non-thermal electrons (NTEs) carried the external energy to the flare. The NTEs energy flux was derived from a non-thermal component seen in RHESSI spectra. The main geometrical parameters of the flare were derived using restored RHESSI imaging data. We found that the variations of the X-ray fluxes recorded in various energy bands and the variations of the H-alpha intensities were well correlated in time during the pre-impulsive and impulsive phases of the flare and they agreed with the variations of the calculated position and vertical extent of the EDL. The variations of the emission noticed in various parts of the H-alpha line profile were caused by individual episodes of energy depositionby the beams of NTEs of various energy spectra on various depths in the chromospheric plasma. These results supplement our previous findings for the solar flare on 21 June2013, having nearly the same GOES-class of C1.1 but HXR emission below 34 keV only (Falewicz et al. 2017) (hereafter Paper I).

arXiv comment18 pages, 11 figures

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