Interpretation of prolonged millimeter-wave emission from a flare using model calculations
Abstract
The long-duration radio flare on June 27, 1993 was characterized by strong emission at millimeter waves (up to 60 sfu at 35 GHz). It was not possible to fit the spectrum by model calculations assuming only one (even inhomogeneous and non-thermal) source because of the increasing flux between 10 and 35 GHz. Either the low-frequency part would be totally suppressed by the strong thermal bremsstrahlung of cool (<106K) plasma necessary for the high mm-flux or the spectral slope would be always negative for ν > 10 GHz if gyrosynchrotron emission dominates. The only way to achieve a sufficient fit was the assumption of two independent sources, one with energetic electrons and enhanced plasma temperature (loop-like structure), the other with rather high electron densities, large source dimensions, and low temperatures (evaporated plasma), both located inside the antenna beam of 2.4 arc min.
- Publication:
-
Solar Variability: From Core to Outer Frontiers
- Pub Date:
- December 2002
- Bibcode:
- 2002ESASP.506..299H
- Keywords:
-
- Sun: Radio Radiation;
- Flares;
- Radiation Mechanisms: Non-Thermal