Calderon, the Secular Plays

González, Cristina Garrigós; Horst, Robert ter

doi:10.2307/341485

Cited by 1 publication

(2 citation statements)

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“…It is certainly violated during large flares with re-structuring of the global magnetic topology. Also, it does not formally account for the continuous footpoint motion driving the Parker (1983) scenario. However, it may be a reasonable approximation for medium-size flares, where the Parker mechanism does not destroy the overall magnetic field structure.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…The electric fields envisaged above are of macroscopic and dissipative nature, and mark the irreversible release of non-potential magnetic energy. We thus follow a scenario, proposed by Parker (1972Parker ( ,1983Parker ( ,1993, where the random photospheric footpoint motion twists and shears the coronal magnetic loops such as to develop tangential discontinuities. This happens intermittently and in multiple localized regions throughout the solar corona, and does not generally imply loop instability or global re-structuring of the solar corona.…”

Section: Introductionmentioning

confidence: 99%

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Gyrokinetic electron acceleration in the force-free corona with anomalous resistivity

Arzner

Vlahos

2006

A&A

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Aims. We numerically explore electron acceleration and coronal heating by dissipative electric fields. Methods. Electrons are traced in linear force-free magnetic fields extrapolated from SOHO/MDI magnetograms, endowed with anomalous resistivity (η) in localized dissipation regions where the magnetic twist ∇ ×b exceeds a given threshold. Associated with η > 0 is a parallel electric field E = ηj which can accelerate runaway electrons. In order to gain observational predictions we inject electrons inside the dissipation regions and follow them for several seconds in real time.Results. Precipitating electrons which leave the simulation system at height z = 0 are associated with hard X rays, and electrons which escape at height z ∼ 3·10 4 km are associated with normal-drifting type IIIs at the local plasma frequency. A third, trapped, population is related to gyrosynchrotron emission. Time profiles and spectra of all three emissions are calculated, and their dependence on the geometric model parameters and on η is explored. It is found that precipitation generally preceeds escape by fractions of a second, and that the electrons perform many visits to the dissipation regions before leaving the simulation system. The electrons impacting z = 0 reach higher energies than the escaping ones, and non-Maxwellian tails are observed at energies above the largest potential drop across a single dissipation region. Impact maps at z = 0 show a tendency of the electrons to arrive at the borders of sunspots of one polarity. Conclusions. Although the magnetograms used here belong to non-flaring times, so that the simulations refer to nanoflares and 'quiescent' coronal heating, it is conjectured that the same process, on a larger scale, is responsible for solar flares.

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Section: Summary and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%