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E.J. Noonan, D.W. Longcope (Montana State U.)
Several authors have proposed solar flare models in the form of cellular automota, sometimes called sandpile models (Lu and Hamilton 1991, Vlahos et al. 1995). Such models are chiefly motivated by the observation that flare-frequency is related to flare-amplitude by a power-law. We propose an alternative derivation for a cellular automoton model, based on reconnection along separators in a complex active-region magnetic field. We present an example in which a two-dimensional array of photospheric flux elements is sheared. Stresses develop along magnetic separators, and are sporadically relieved by reconnection episodes (flares) of varying sizes. A larger event occurs when reconnection on one separator triggers reconnection on neighboring separators through mutual inductance. This reconnection-propagation can be reduced to a simple set of rules (a cellular automoton), which differ from those derived by previous authors. In addition, we show that the implimentation of our model results in a power-law size/frequency distribution in agreement with observations. The power-law index also differs from those found in previous two-dimensional sandpile models.
This material is based upon work supported by the National Science Foundation under Grant No. ATM-9733424.
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