Observation of solar flare SOL 2015–10–01 and calculation of its radiation within the model of superposition of heated layers

Abstract

The purpose of the work is to study the behavior of intensity curves emission in the Hα, Hβ, D3, H Ca II, and Ca IR 8542 Å lines in the process of development of the flare and compare the results with calculated values. Observations were carried out with the horizontal solar telescope HSFA-2 (Ondrejov Observatory) using CCD arrays. For processing we selected the 2015–10–01 flare of class M 4.5 in the NOAA active region 12422 for which the absolute values of the fluxes in spectral lines were determined. It is shown that the model of heating of the chromospheric gas by the flow of magnetohydrodynamic waves from the convective zone and its ionization and excitation by the flow of suprathermal particles from the corona satisfies the observations. Calculations are performed in the lines of hydrogen, the Ca II ion, and the helium atom, taking into account the main processes determining the radiation of gas that is opaque in spectral lines. It is shown that at the onset of the flare, the emission in the Ca II lines comes from a cold region, with a temperature of about 5400 K, in the sunspot penumbra. The flat decrement of the Balmer series coupled with a large flux in the calcium lines indicates the inhomogeneity of the radiating region along the vertical. The emission in the helium D3 line is largely due to suprathermal particles.