Decimetric gyrosynchrotron emission during a solar flare
A decimetric, microwave, and hard X-ray burst has been observed during a solar flare in which the radio spectrum below peak plux fits an f/sup +2/ power law over more than a decade in frequency. The spectrum is interpreted to mean that the radio emission originated in a homogeneous, thermal, gyrosynchrotron source. Thiis is the first time that gyrosynchrotron radiation has been identified at such low decimetric frequencies (900-998 MHz). The radio emission was cotemporal with the largest single hard X-ray spike burst ever reportd. The spectrum of the hard X-ray burst can be well represented by a thermal bremsstrahlung function over the energy range from 30 to 463 keV at the time of maximum flux. The temporal coincidence and thermal form of both the X-ray and radio spectra suggest a common source electron distribution. The unusual low-frequency extent of th single-temperature thermal radio spectrum and its association with the hard X-ray burst imply that the source had an area approx.10/sup 18/ cm/sup 2/, a temperature approx.5 x 10/sup 8/ K, an electron density < or =7 x 10/sup 9/ cm/sup -3/, and a magnetic fiel of approx.120 gauss. H..cap alpha.. and 400--800 MHz evidence suggest that a loop structure of length > or =10,000 km existed in the flare active region which could have been the common, thermal source of the observed impulsive emissions.
- Research Organization:
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina
- OSTI ID:
- 6196233
- Journal Information:
- Astrophys. J.; (United States), Vol. 280:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
SOLAR FLARES
RADIOWAVE RADIATION
SYNCHROTRON RADIATION
SUN
SOLAR X-RAY BURSTS
HARD X RADIATION
MHZ RANGE 100-1000
BREMSSTRAHLUNG
ELECTROMAGNETIC RADIATION
FREQUENCY RANGE
IONIZING RADIATIONS
MAIN SEQUENCE STARS
MHZ RANGE
RADIATIONS
SOLAR ACTIVITY
STARS
X RADIATION
640104* - Astrophysics & Cosmology- Solar Phenomena