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Astron. Astrophys. 355, 355-364 (2000)

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Small and large scale magnetic structures involved in the development of the 1992 October 28 solar flare

J.-P. Raulin 1, N. Vilmer 2, G. Trottet 2, N. Nitta 3, A.V.R. Silva 1, P. Kaufmann 1, E. Correia 1 and A. Magun 4

1 CRAAE/CRAAM, Instituto Presbiteriano Mackenzie, Rua da Consolação 896, 01302-907, São Paulo, Brazil (raulin@craae.mackenzie.br)
2 DASOP, CNRS-URA 8046, Observatoire de Paris, Section de Meudon, 92195 Meudon, France
3 Lockheed Martin Solar & Astrophysics Laboratory, Dep/L9-41, B/252, 3251 Hanover St., Palo Alto, CA 94304, USA
4 Institute of Applied Physics, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland

Received 7 July 1999 / Accepted 17 December 1999


We report spatially resolved observations of a solar flare, obtained in a wide range of wavelengths including soft and hard X-rays, decimeter-meter and millimeter radio emissions. This unique combination of data (including the simultaneous fast localization of emission at millimeter wavelengths) allows us to conclude that, even if the 1992 October 28 flare is a moderate one in terms of the amount of energy contained in the thermal plasma and in non thermal electrons, the magnetic configuration involved in the flare development is complex at all spatial scales. Furthermore, it is shown that stepwise temporal evolutions of the amount of energy release in non thermal electrons are closely related to stepwise changes of the magnetic structures of all spatial scales illuminated either by hot plasma or by non-thermal electrons. This provides some evidence that different episodes of energy release are triggered by loop-loop interaction and that the site of particle acceleration changes rapidly within the energy release volume. These findings are discussed in the context of flare models as well as with respect to the fragmented nature of energy release in solar flares.

Key words: Sun: activity – Sun: flares – Sun: particle emission – Sun: radio radiation

Send offprint requests to: J.-P. Raulin

© European Southern Observatory (ESO) 2000

Online publication: March 17, 2000