The role of betatron acceleration in complex solar bursts |
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| Authors: | Judith T Karpen |
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| Institution: | (1) Laboratory for Astronomy and Solar Physics, NASA-Goddard Space Flight Center, U.S.A.;(2) Astronomy Program, University of Maryland, U.S.A.;(3) Present address: Code 4169K, E. O. Hulburt Center for Space Research, Naval Research Laboratory, 20375 Washington, D.C., U.S.A. |
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| Abstract: | The betatron mechanism was proposed by Brown and Hoyng (1975) as a means of producing the continuous, quasi-periodic electron acceleration which may occur in long-lasting hard X-ray events. In the present work, two pertinent facets of the betatron model are investigated: The possibility that the multiplicity characteristic of complex impulsive bursts is due to the betatron process; and the possibility that some or all of the second-stage emission during two-stage bursts can be attributed to betatron acceleration. To test for the pattern of X-ray spectral behavior predicted by the betatron model, a number of multiply-impulsive events (cf., Karpen et al., 1979) and two-stage bursts (cf., Frost and Dennis, 1971) were selected from the OSO-5 hard X-ray spectrometer data for in-depth analysis. The purely impulsive emissions show no signs of the effects of betatron action, thus eliminating this process as a potential source of impulsive-phase multiplicity. However, the spectral characteristics determined during the first few minutes of the second stage are found to be consistent with the predictions of the betatron model for the majority of the two-stage events studied. The betatron-acceleration mechanism thus is proposed as a common second-stage phenomenon, closely associated with the diverse phenomena at other wavelengths which characterize this phase of emission. The physical significance of the source parameters derived according to the model-fitting procedure are discussed in detail, and the role of the betatron process is evaluated in the broader context of present-day concepts of the second stage. |
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