Issue |
Astron. Astrophys. Suppl. Ser.
Volume 135, Number 3, March II 1999
|
|
---|---|---|
Page(s) | 415 - 427 | |
DOI | https://doi.org/10.1051/aas:1999182 | |
Published online | 15 March 1999 |
The limb flare of November 2, 1992: Physical conditions and scenario
1
Institute of Solar-Terrestrial Physics, Lermontov St. 126, Irkutsk 664033, Russia
2
Nobeyama Radio Observatory, NAOJ, Minamimaki, Minamisaku, Nagano 384-1305, Japan
Send offprint request to: A.T. Altyntsev
Received:
15
June
1998
Accepted:
3
November
1998
The powerful X9 class flare was investigated using interferometric data of
Nobeyama Radioheliograph (17 GHz) and SSRT (5.7 GHz).
According to images obtained in circular polarization, it was
found that the microwave burst was generated consequently in the sites, where
opposite magnetic loops were in the close contact.
Steady exponential growth of the total microwave flux in the initial
stage of the flare under significant reconstruction of the radio sources
certifies that the development of the flare was conducted by some large-scale
instability.
Radiation during the impulsive phase was produced by gyrosynchrotron
emission of electrons trapped within a wide dome-like volume with
G and
cm-3.
In the decay phase, the emission at higher frequencies was mainly produced
by bremsstrahlung from high loops emitting soft X-rays.
There is evidence of the energy release long after the impulsive
phase: an intensive, rather compact microwave source in the locus
of contact of two oppositely polarized regions in these loops
and sub-bursts during 2 hours after the peak at low heights.
For the first time, a compact source of the sub-second pulses at 17 GHz
was found to be located as high as
km. They were due to
gyrosynchrotron emission.
Key words: Sun: flares / magnetic fields / particle emission, radio radiation / X-rays
© European Southern Observatory (ESO), 1999