Requirements for the number of nonthermal electrons which must be accelerated in the impulsive phase of a flare are reviewed. These are uncertain by two orders of magnitude depending on whether hard X-rays above 25 keV are produced primarily by hot thermal electron.,; which contain a small fraction
Gamma-ray and microwave evidence for two phases of acceleration in solar flares
โ Scribed by T. Bai; R. Ramaty
- Publisher
- Springer
- Year
- 1976
- Tongue
- English
- Weight
- 799 KB
- Volume
- 49
- Category
- Article
- ISSN
- 0038-0938
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โฆ Synopsis
Relativistic electrons in large solar flares produce gamma-ray continuum by bremsstrahlung and microwave emission by gyrosynchrotron radiation. Using observations of the 1972, August 4 flare, we evaluate in detail the electron spectrum and the physical properties (density, magnetic field, size, and temperature) of the common emitting region of these radiations. We also obtain information on energetic protons in this flare by using gamma-ray lines. From the electron spectrum, the proton-toelectron ratio, and the time dependences of the microwave emission, the 2.2 MeV line and the gamma-ray continuum, we conclude that in large solar flares relativistic electrons and energetic nuclei are accelerated by a mechanism which is different from the mechanism which accelerates~< 100 keV electrons in flares.
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I have studied the observational relationship between the location of flare sites in active regions and three other observables, viz., Ha line width, hard X-ray burst parameters, and peak microwave fluxes. Results suggest that the strength of the magnetic field plays a role in governing the magnitud