Issue |
A&A
Volume 366, Number 1, January IV 2001
|
|
---|---|---|
Page(s) | 326 - 330 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361:20000221 | |
Published online | 15 January 2001 |
High-sensitivity observations of solar flare decimeter radiation
Institute of Astronomy, ETH-Zentrum, 8092 Zurich, Switzerland
Corresponding author: A. O. Benz, benz@astro.phys.ethz.ch
Received:
25
May
2000
Accepted:
7
November
2000
A new acousto-optic radio spectrometer has observed the GHz radio emission
of solar flares with unprecedented sensitivity. The number of detected decimeter
type III bursts is greatly enhanced compared to observations by conventional
spectrometers observing only one frequency at the time. The observations
indicate a large number of electron beams propagating in dense plasmas. For the first time, we report weak, reversed drifting type III bursts at frequencies above simultaneous narrowband
decimeter spikes. The type III bursts are reliable signatures of electron beams
propagating downward in the corona, apparently away from the source of the
spikes. The observations contradict the most popular spike model that places the spike sources at the footpoints of loops. Conspicuous also was an apparent bidirectional type U burst forming a fish-like pattern. It occurs simultaneously with an intense U-burst at
MHz observed in Tremsdorf. We suggest that it intermodulated with strong terrestrial interference (cellular phones) causing a spurious symmetric pattern in the spectrogram at 1.4 GHz. Symmetric features in the
GHz range, some already reported in the literature, therefore must be considered with utmost caution.
Key words: acceleration of particles / Sun: corona / Sun: flares / Sun: magnetic fields / Sun: radio radiation
© ESO, 2001
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