Observations of high brightness temperatures in moving type IV solar radio bursts.
Abstract
Observational evidence is presented for three moving type IV bursts at 43, 80, and 160 MHz with brightness temperatures of the order of 1 billion K, as well as for another such burst at 43 MHz with a brightness temperature as high as 10 billion K. It is found that approximately 10 to the 33rd electrons with energies of at least 1 MeV are required to explain such high brightness temperatures in terms of incoherent gyrosynchrotron radiation. This number of energetic electrons is shown to be near the upper limit for the number of fast electrons accelerated in the second phase of a solar flare. Alternative explanations considered include coherent (amplified) gyrosynchrotron radiation and amplified plasma radiation at the fundamental or second-harmonic plasma frequency. It is concluded that a smaller number of electrons with energies around 100 keV would be required if the emission is amplified.
- Publication:
-
Publications of the Astronomical Society of Australia
- Pub Date:
- 1978
- DOI:
- 10.1017/S1323358000015411
- Bibcode:
- 1978PASA....3..247S
- Keywords:
-
- Brightness Temperature;
- Radio Astronomy;
- Solar Temperature;
- Type 4 Bursts;
- Plasma Radiation;
- Radio Bursts;
- Synchrotron Radiation;
- Solar Physics;
- Brightness Temperatures:Solar Radio Bursts