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| Titel |
Self-organized criticality in solar flares: a cellular automata approach |
| VerfasserIn |
L. F. Morales, P. Charbonneau |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 17, no. 4 ; Nr. 17, no. 4 (2010-07-22), S.339-344 |
| Datensatznummer |
250013704
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| Publikation (Nr.) |
 copernicus.org/npg-17-339-2010.pdf |
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| Zusammenfassung |
| We give an overview of a novel lattice-based avalanche model that reproduces
well a number of observed statistical properties of solar flares. The
anisotropic lattice is defined as a network of vertically-connected nodes
subjected to horizontal random displacements mimicking the kinks introduced
by random motions of the photospheric footpoints of magnetic fieldlines
forming a coronal loop. We focus here on asymmetrical driving displacements,
which under our geometrical interpretation of the lattice correspond to a net
direction of twist of the magnetic fieldlines about the loop axis. We show
that a net vertical electrical current density does build up in our lattice,
as one would expect from systematic twisting of a loop-like magnetic
structure, and that the presence of this net current has a profound impact on
avalanche dynamics. The presence of an additional energy reservoir tends to
increase the mean energy released by avalanches, and yield a probability
distribution of released energy in better agreement with observational
inferences than in its absence. Symmetrical driving displacements are in
better conceptual agreement with a random shuffling of photospheric
footpoint, and yield a power-law distribution of energy release with exponent
larger than 2, as required in Parker's nanoflare model of coronal heating. On
the other hand, moderate asymmetrical driving generate energy distribution
exponents that are similar to those obtained from SOHO EUV observations. |
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