Electron acceleration in impulsive solar flares

Journal Article · Wed Dec 01 00:00:00 EST 1982 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/160514· OSTI ID:5577396

Kane, S R; Benz, A O; Treumann, R A

Simultaneous observations of the hard X-ray, microwave, and type III and DCIM (decimetric)radio bursts associated with the 1978 December 4 solar flare have been used to study the physical parameters relevant to the acceleration and propagation of energetic electrons during the impulsive phase of a solar flare. The hard X-ray observations were made with the X-ray spectrometer aboard the ISEE 3 spacecraft. The radio spectra in metric and decimetric bands were recorded with the radiospectrograph located at Durnten, near Zurich, Switzerland. The microwave observations were made at the Sagamore Hill and Bern observatories. The three metric type III bursts coincided with the three most prominent hard X-ray peaks. This is the fist time a clear one-to-one association between single type III bursts and hard X-ray peaks has been established. The average delay of the type III bursts with respect to the X-ray peaks was 0.5 s. The harder the X-ray spectrum, the higher was the drift rate of the associated type III burst. The characteristic electron energies inferred from the drift rate are of the order of 70 keV. The observed increase in the high-frequency cutoff of the metric type III bursts during the impulsive phase has been examined in terms of the decreasing altitude of the electron acceleration/injection region, the increasing hardness of the electron spectrum, and the decreasing acceleration time. A pulsating decimetric continuum (DCIM) was also found to be present during and before the impulsive phase. The DCIM source seems to coincide spatially with the electron acceleration region and the (projected) origin of the associated type II shock.ction region.

• Research Organization: Space Sciences Laboratory, University of California, Berkeley
• OSTI ID: 5577396
• Journal Information: Astrophys. J.; (United States), Vol. 263:1
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
SOLAR ELECTRONS
PLASMA ACCELERATION
SOLAR FLARES
EMISSION SPECTRA
X-RAY SPECTRA
HARD X RADIATION
SOLAR RADIO BURSTS
SOLAR RADIOWAVE RADIATION
ACCELERATION
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
IONIZING RADIATIONS
LEPTONS
RADIATIONS
RADIOWAVE RADIATION
SOLAR ACTIVITY
SOLAR PARTICLES
SOLAR RADIATION
SPECTRA
STELLAR RADIATION
X RADIATION
640104* - Astrophysics & Cosmology- Solar Phenomena