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Astron. Astrophys. 326, 1228-1234 (1997)

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Nonlocal communication in self-organising models
of solar flare occurrence

A.L. MacKinnon 1 and K.P. Macpherson 2

1 Dept. of Adult and Continuing Education, University of Glasgow, Glasgow, G12 8QQ, UK
2 Dept. of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK

Received 31 October 1996 / Accepted 23 May 1997


Recent avalanche models of solar flare occurrence which consider the magnetised solar atmosphere to be in a state of self-organised criticality have concentrated mainly on the magnetic field as the means by which individual energy release sites communicate with neighbouring sites. This, however, neglects the possibility of remote triggering of energy release via fast particles. In this paper we augment the standard avalanche models of flare occurrence to include this possibility of `non-local' communication between sites. Non-local communication with just one or two remote sites does not observably modify the flare size distribution (this quantity remains consistent with observations). Non-local triggering of too many remote sites can, however, destroy the self-organised critical state. Our simulations also produce more general conclusions on the robustness of the self-organised critical state.

Key words: Sun: flares - Sun: corona - Sun: magnetic fields - Sun: X-rays, gamma rays

Present address: Dept. of Theoretical Physics, Oxford University, 1 Keble Road, Oxford OX1 3NP, UK

Send offprint requests to: K.P. Macpherson


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© European Southern Observatory (ESO) 1997

Online publication: April 8, 1998