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Solar flare particle heating via low-β reconnection

Published online by Cambridge University Press:  01 August 2006

Dietmar Krauss-Varban
Affiliation:
Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450, USA
Brian T. Welsch
Affiliation:
Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450, USA
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Abstract

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Observations give tight constraints on the temporal and spatial scales of particle heating in solar flares, and on the required efficiency. Electrons are accelerated into a quasi-thermal population of a few tens of keV. X- and γ-rays imply tails in electron and ion distributions reaching tens of MeV and above. Simple estimates indicate that all available electrons are accelerated at least once to moderate energies, pointing to an initial process resembling bulk heating rather than acceleration of a small or localized population. In the absence of effective collisions, wave-particle interactions are the prime candidate. Here we address the outstanding questions, (i) what process can heat the entire reconnecting plasma to the above energies, and (ii) what provides the free energy for wave-particle interactions? We propose a process in which initially the ions are heated and provide the free energy for electron heating and tail formation.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2007

References

Krauss-Varban, D., & Omidi, N. 1995, Geophys. Res. Lett., 22, 3271CrossRefGoogle Scholar
Gosling, J.T., Skoug, R.M., McComas, D.J., & Smith, C.W. 2005, J. Geophys. Res., 110, A01107CrossRefGoogle Scholar