Abstract
Abstract. We present results of the 18 August 2002 flare analysis as an example for developing a diagnostic tool for thermal and non-thermal processes in chromospheric lines. Taking into account the hard X-ray (HXR) emission, we attempted to derive the Hα and Hβ line properties which were caused by the non-thermal electron contribution and could be useful for diagnostic purposes. The flare itself was a sequence of harder and softer bursts in HXR and we investigated three flare kernels associated with them. Two of the kernels appeared simultaneously. This phase of the flare could be observed in a broad band of wavelengths (HXR, UV, optical and microwaves). Kernel 1 did not clearly coincide with any HXR source but its intensity increased with the HXR flux rise. The flare kernel~3 did not show any significant response in microwaves, however, the related HXR flux was comparable with the flux of the previous kernels. We carried out an analysis of the difference between the Hα/Hβ profile rate in the line center at the distance of 0.5 Å from the line center. Only kernel 2 showed parameter fluctuations that were related to HXR flux evolution. The supposition of the non-thermal electron effect on the Hα/Hβ profile ratio was confirmed only at the kernel connected with the 25–50 keV HXR source. We found further confirmation that the Hα/Hβ line intensity ratio could be used as a diagnostic tool for non-thermal electron presence.
Highlights
The energy storage, release and transport are still hot and enigmatic problems of solar physics
In the kernel identified with the hard X-ray (HXR) source position we found that the profiles of the Hα/Hβ line ratio displayed a peculiar pattern
We can carry out a more detailed analysis of the photon energy spectra but from the obtained results it is obvious that the non-thermal electrons were present in the flare
Summary
The energy storage, release and transport are still hot and enigmatic problems of solar physics. It is accepted that the solar flare energy is initially released in the corona and transported by various means from the primary release site to the chromosphere. The role of denser chromospheric layers, where most of the flare energy is dissipated radiatively, is not minor but quite a substantial one (Heinzel, 2003; Hudson, 2007). The understanding of the energy release/transport mechanisms in solar flares is closely connected with the lower atmosphere response. The accelerated or non-thermal particle beams are the fastest and most effective transportation agents. The presence of accelerated particles in solar flares is without any doubts. A definite mechanism of their effect on the solar atmosphere has not been accepted yet
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