Topological changes of the photospheric magnetic field inside active regions: A prelude to flares? |
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Authors: | Luca Sorriso-Valvo Vincenzo Carbone Valentina I. Abramenko Alain Noullez Annick Pouquet |
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Affiliation: | a Dipartimento di Fisica and Istituto Nazionale di Fisica per la Materia, Ponte P. Bucci, Cubo 31C, Università della Calabria, Roges di Rende I-87036 (CS), Italy b Crimean Astrophysical Observatory, 98409 Nauchny, Crimea, Ukraine c Laboratoire Cassini, Observatoire de la Côte d'Azur, B.P. 4229, F-06304 Nice Cedex 04, France d ASP/NCAR, P.O. Box 3000 Boulder, CO 80307-3000, USA e Big Bear Solar Observatory, 40386 North Shore Lane, Big Bear City, CA 92314-9672, USA |
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Abstract: | The detection of magnetic field variations as a signature of flaring activity is one of the main goals in solar physics. Past efforts gave apparently no unambiguous observations of systematic changes. In the present study, we discuss recent results from observations that scaling laws of turbulent current helicity inside a given flaring active region change in response to large flares in that active region. Such changes can be related to the evolution of current structures by a simple geometrical argument, which has been tested using high Reynolds number direct numerical simulations of the MHD equations. Interpretation of the observed data within this picture indicates that the change in scaling behavior of the current helicity seems to be associated with a topological reorganization of the footpoint of the magnetic field loops, namely with the dissipation of small scales structures in turbulent media. |
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Keywords: | Active regions Flares |
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