Up: The limb flare of
- 1.
- It has appeared to be possible, to explain the main qualities of the
flare within the framework of a closed configuration.
- 2.
- Studying how the pre-flare spatial structure developed has revealed the
regions in which the line-of-sight component of the magnetic field had the
opposite direction. The LCP-region was almost enveloped by the RCP one. In
the course of the flare, energy release sites appeared near the boundary
between these regions.
- 3.
- Microwave sources of different origin were observed during the flare.
The source with the spectral turnover frequency <10 GHz corresponded to the
energy release site and provided the main contribution into the total flux
of the burst in the initial phase of the flare. When the burst reached its
peak, the turnover frequency became two times more. Trapped electrons were
responsible for the most part of the microwave emission during the impulsive
phase.
- 4.
- The steady exponential growth of the brightness temperature and the flux
of the microwave emission went on in the initial stage of the flare during an
interval as long as almost 5 time constants. Sources essentially changed
their spatial structure during this stage. So the development of the flare
was conducted by some large-scale instability.
- 5.
- Sub-second pulses observed at 5.7 GHz during the impulsive phase were
generated in the optically thin source which was observed in hard X-rays at a
height of
km. The compact source of the sub-second pulses at
17 GHz was due to gyrosynchrotron emission of electrons with the energy of
1-2 MeV. It had the size of 
km and was located at a height
of 
km.
- 6.
- The energy release had not yet terminated during the post-flare stage
till at least 06:00. Two regions of energy release can be followed in
this stage: the upper one where the two opposite magnetic ropes contacted, and
the lower one where the microwave sub-bursts of non-thermal origin occurred.
Free-free emission from soft X-ray loops then became predominant.
Acknowledgements
A. Altyntsev and V. Grechnev use this opportunity to express their thanks
for hospitality and help from the Nobeyama Solar Group during their work in
Nobeyama Radio Observatory.
We thank Dr. B. Lubyshev and Ms. G. Zubkova for a preliminary analysis
of the SSRT data. We are greatly indebted to Dr. R. Ramaty for his kindness,
to have made his code for calculation of gyrosynchrotron emission available for us.
Part of this work was supported by the Russian projects of RFFI
No. 96-02-16648, No. 97-02-16906 and Astronomia.
Up: The limb flare of
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