PREDNASAJUCI / LECTURER :
Krzysztof Radziszewski
Astronomical Institute, Wroclaw University, Poland

NAZOV / TITLE :
The observations of solar phenomena by SECIS system.

ABSTRAKT / ABSTRACT :
Since 2003 the Solar Eclipse Coronal Imaging System SECIS has been used for
non-eclipsing high time resolution observations of solar flares. The results
of a search for fast changes of solar flare H-alpha emission correlated in
time with variations of hard X-ray (HXR) fluxes recorded with the Reuven
Ramaty High Energy Solar Spectroscopic Imager (RHESSI) are presented. Using
the Large Coronagraph (LC), Multi-Channel Subtractive Double Pass (MSDP)
spectrograph and the SECIS Instrument at the Białkow Observatory, we
collected a total of 47 sets of high time resolution (0.04-0.075 s)
observations of H-alpha bright flare kernels during years 2003 - 2005. For
the first time, several-minute-long high-resolution observations of the
H-alpha line profiles as well as simultaneous two-dimensional images have
been obtained with time resolution much better than 1 s.
For many examples we have found very good time correlations between HXR flux
variations and variations of the H-alpha emission of the selected bright
flaring kernels. The H-alpha emission often follows the 20-50 keV X-ray
emission by 1-2 s. There are also several examples of impulsive increases in
softer 10-20 keV emission which appear to be of nonthermal origin. These
results are consistent with previous observations and with theoretical
studies in which the chromospheric response to energetic beamed electrons is
calculated, provided that the chromospheric hydrogen densities are
relatively high (10e14-10e15 cm-3).
We present also the results of measures of areas of H-alpha flaring kernels
in various depth in solar chromosphere as well as interaction of non-thermal
electrons with solar corona and chromosphere during solar flares.