Academy of Sciences of the Czech Republic
X-Ray Flare Emission
X-ray emission of hot solar plasma (mostly observed in solar
flares) is an important source of information on physical
processes which we would like to understand in more detail.
Non-thermal X-ray emission may help to discover acceleration
mechanisms causing beams of particles to be accelerated to
very high energies in solar flares. Unfortunately, the
short-wavelength band of the electromagnetic spectrum is
absorbed by the Earth's atmosphere and can be observed from
spacecraft only. The group activities are therefore focused
on scientific analysis of top-quality satellite data obtained
in broad international cooperation as well as on development
of its own instruments for space projects.
F.Farnik closely collaborates with the 'Yohkoh group', the
scientific investigators operating the Japanese Yohkoh
satellite, (he has spent nearly half a year so far in Japan)
and studies the physical relation between pre-flare
brightenings and following flares as well as large coronal
structures observed in X-rays (together with Zdenek Svestka
from the Netherlands). He is also the principal investigator
of two instruments (hard X-ray spectrometers) which are under
development for the European CESAR project (the project which
is led by the Italian Space Agency, to be launched in 2000)
and for a DoD (USA) satellite (to be launched in 1999 as
a flare forecaster, in cooperation with the Space Environment
Laboratory in Boulder).
M.Varady tries to model physical processes in flaring loops
mathematically and to compare his results with observations
from the Yohkoh satellite.
J.Kreckova supports the group by necessary programming and
computers managing. She is also helpful to other groups and
departments solving network and system problems.
So far we have failed to launch our own instrument into orbit
(both projects we are participating in have been delayed) and
therefore we depend on data from other projects. Analysis of
Yohkoh data in broad international collaboration has enabled
us to publish classification and description of large coronal
structures observed in soft X-rays. Two papers were already
published and another two are under final preparation.
Studies of pre-flare brightenings led to an important
conclusion that these brightenings originate at
approximatelly the same altitude as the following flares;
also this topic is still under more thorough study.