THE STATISTICAL PHYSICS OF SOLAR ACTIVE REGIONS AND THE FUNDAMENTAL NATURE OF SOLAR-FLARES

We demonstrate that solar active regions are examples of a class of driven dissipative systems whose long-term statistical behavior is characterized by a power-law distribution of energy-dissipating avalanches (Lu 1995a). This explains why solar flares are power-law distributed, as well as how the long-time macroscopic behavior of solar active regions can be well approximated and understood using simple cellular automata models (Lu and Hamilton 1991; Lu et al. 1993). This work represents a first step toward understanding the macroscopic statistical physics of active regions and the fundamental nature of solar flares.