Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evolution of Flare Ribbons, Electric Currents and Quasi-separatrix
  Layers During an X-class Flare   The standard model for eruptive flares has in the past few years been
extended to 3D. It predicts typical J-shaped photospheric footprints of the
coronal current layer, forming at similar locations as the Quasi-Separatrix
Layers (QSLs). Such a morphology is also found for flare ribbons observed in
the EUV band, as well as in non-linear force-free field (NLFFF) magnetic field
extrapolations and models. We study the evolution of the photospheric traces of
the current density and flare ribbons, both obtained with the SDO instruments.
We investigate the photospheric current evolution during the 6 September 2011
X-class flare (SOL2011-09-06T22:20) from observational data of the magnetic
field obtained with HMI. This evolution is compared with that of the flare
ribbons observed in the EUV filters of the AIA. We also compare the observed
electric current density and the flare ribbon morphology with that of the QSLs
computed from the flux rope insertion method/NLFFF model.
  The NLFFF model shows the presence of a fan-spine configuration of overlying
field lines, due to the presence of a parasitic polarity, embedding an
elongated flux rope that appears in the observations as two parts of a
filament. The QSLs, evolved via a magnetofrictional method, also show similar
morphology and evolution as both the current ribbons and the EUV flare ribbons
obtained at several times during the flare. For the first time, we propose a
combined analysis of the photospheric traces of an eruptive flare, in a complex
topology, with direct measurements of electric currents and QSLs from
observational data and a magnetic field model. The results, obtained by two
different and independent approaches, 1) confirm previous results of current
increase during the impulsive phase of the flare, 2) show how NLFFF models can
capture the essential physical signatures of flares even in a complex magnetic
field topology.

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The categories of this paper are: dg-ga
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The categories of this paper are: physics
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The categories of this paper are: alg-geom
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The categories of this paper are: chem-ph
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The categories of this paper are: stat
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: cs
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-th
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The categories of this paper are: atom-ph
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The categories of this paper are: adap-org
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The categories of this paper are: eess
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The categories of this paper are: ao-sci
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The categories of this paper are: plasm-ph
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The categories of this paper are: patt-sol