The Depth and the Vertical Extent of the Energy Deposition Layer in a Medium-class Solar Flare

Abstract

Abstract We analyze here variations of the position and the vertical extent of the energy deposition layer (EDL) in the C1.6 GOES-class solar flare observed at 10:20 UT on 2012 September 10. The variations of the EDL are contrasted with the variations of the spectra and emission intensities recorded in the Hα line with very high time resolution using the MSDP spectrograph at Białków 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 nonthermal electrons (NTEs) carried the external energy to the flare. The energy flux of the NTEs was derived from a nonthermal 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 Hα 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 Hα line profile were caused by individual episodes of energy deposition by 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 2013 June 21, having nearly the same GOES class of C1.1 but HXR emission below 34 keV only.