Monday

Observations of an X1 class WL solar flare on 11 June 2014 showed surprisingly weak emission in both Balmer and Lyman lines. The flare was observed by RHESSI satellite but an analysis of particle beams was inconclusive, especially in determining low cut-off energy of the beams. We performed a grid of models using radiative hydrodynamic code RADYN in order to compare synthetic spectra with observations. The flux of non-thermal electron beams was estimated from RHESSI analysis and an area of WL emission observed by HMI/SDO as 3E9, E10 and 3E10 erg/cm2/s. For low energy cut-off we chose a range from 20 to 120 keV with a step of 20 keV and delta parameter equal to 3.
Models show that higher low energy cut-off is more likely to produce an absorption Balmer line profile, if the total energy flux remains relatively low. If an emission in wings of the line appear, it tends to form later during the simulation. Atmospheric temperature profile shows that for higher values of low energy cut-off the energy of the beam is deposited lower in chromosphere or even in temperature minimum region. This finding suggests, that suppressed hydrogen emission can indicate a formation of white-light continuum below chromosphere.