The nature of decimeter-wave microburst emission |
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Authors: | V M Bogod L V Yasnov |
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Institution: | (1) St. Petersburg Branch of the Special Astrophysical Observatory, Russian Academy of Sciences, Pulkovo, St. Petersburg, 196140, Russia;(2) Research Institute of Radiophysics, St. Petersburg State University, Ul’yanovskaya ul. 1, Staryi Peterhof, St. Petersburg, 198504, Russia |
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Abstract: | New observations of solar microbursts are reported. The spectra of microbursts can contain narrow features (Δf/f ≤ 0.03). Possible mechanisms for the generation of the microburst radio emission are analyzed, focusing on mechanisms that preferentially generate ordinary waves. Together with the well-known generation of radio emission at the fundamental plasma frequency, mechanisms associated with upper-hybrid waves and resonant-transition radiation are considered. The radio emission at the upper-hybrid frequency always corresponds to ordinary waves. Ordinary waves can also dominate in resonant-transition radiation, but the presence of well-developed small-scale turbulence in the emission region is required. Possible mechanisms for the generation of this turbulence include thermal fluctuations, Langmuir turbulence, quasi-stationary structures created by plasmawaves, and ion-acoustic waves. Probable origins of the quasi-periodicity of microbursts are analyzed. |
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