On the nature of some active regions in the microwave range |
| |
Authors: | M Felli G Tofani E Fürst W Hirth |
| |
Institution: | 1. Osservatorio Astrofisico di Arcetri, Florence, Italy 2. Max-Planck-Institut für Radioastronomie, Bonn, Germany 3. Institut für Radioastronomie der Universit?t Bonn, Bonn, Germany
|
| |
Abstract: | The radio emission of a selected number of solar active regions has been investigated with high angular resolution at two frequencies: 10 and 17 GHz. By comparing the results of the two observations the following conclusions can be drawn: - The brightness temperature distribution of an active region is often composed of very bright cores of small dimension (angular extent θ?20″) imbedded in extended halos of lower brightness.
- The radio emission of such structures as well as the degree of polarization can be explained with a thermal process. The halos can originate by pure thermal bremsstrahlung while in the case of the very bright cores found at 10 GHz (brightness temperature T b?1–9 × 106K) the emission at the harmonics of the gyrofrequency is needed.
|
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|