7 research outputs found
The limb flare of November 2, 1992: Physical conditions and scenario
The powerful X9 class flare was investigated using interferometric data of
Nobeyama Radioheliograph (17Â GHz) and SSRT (5.7Â 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 2Â hours after the peak at low heights.
For the first time, a compact source of the sub-second pulses at 17Â GHz
was found to be located as high as  km. They were due to
gyrosynchrotron emission