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Astron. Astrophys. 360, 1163-1169 (2000)

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Emerging flux as a driver for homologous flares

N.D.R. Ranns, L.K. Harra, S.A. Matthews and J.L. Culhane

Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey, RH5 6NT, UK

Received 15 November 1999 / Accepted 16 June 2000


We present multi-wavelength observations of 2 M-class solar flares observed by SoHO and Yohkoh, which appear to be homologous. By examination of the flare loop morphology and footpoints we propose a schematic reconnection scenario of a two loop interaction in a quadrupolar magnetic configuration, for both flares (Machado 1983; Mandrini 1991). After the first flare, the combination of chance emergence of new flux at an opportune location and a subsequent flare, of the type described by Heyvaerts et al. (1977), form a new quadrupolar configuration in which the second flare occurred. Therefore though the two M-class flares are homologous by definition, they appear to conform to a scenario in which the preflare conditions are reformed after the first flare by emerging flux, rather than models which involve the continual shearing of a single magnetic structure.

Key words: Sun: flares

Send offprint requests to: N.D.R. Ranns (ndrr@mssl.ucl.ac.uk)

© European Southern Observatory (ESO) 2000

Online publication: August 23, 2000