The gyro-synchrotron radiation from moving type IV sources in the solar corona

✍ Scribed by G. A. Dulk

• Publisher: Springer
• Year: 1973
• Tongue: English
• Weight: 414 KB
• Volume: 32
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00154962

✦ Synopsis

Calculations of the gyro-synchrotron emission are made for conditions which might be expected in moving type IV sources in the solar corona. Two simple models for an evolving source are treated: a uniform cube and an inhomogeneous sphere. The results suggest that most moving sources have the foUowing features: (1) A rather strong magnetic field, ~ l0 G, is carried out within the source. This is required to achieve the high degree of circular polarization often observed. (2) Synchrotron self-absorption causes the source to be optically thick at frequencies less than about 100 MHz, thus restricting the bandwidth of the radiation. The self-absorption decreases as the source moves outward and expands. The turnover frequency, which sepalates the optically thick and thin spectral regimes, moves rapidly to lower frequencies, accompanied by a change from low to high circular polarization. In the case of an inhomogeneous source, the source appears to be larger at the lower frequencies.

(3) Razin-Tsytovich suppression cannot be an important factor in determining the characteristics of most sources.