Heating and cooling of coronal loops with turbulent suppression of parallel heat conduction

Bian, N., Emslie, A. G., Horne, D. and Kontar, E. P. (2018) Heating and cooling of coronal loops with turbulent suppression of parallel heat conduction. Astrophysical Journal, 852(2), 127. (doi:10.3847/1538-4357/aa9f29)

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Abstract

Using the “enthalpy-based thermal evolution of loops” (EBTEL) model, we investigate the hydrodynamics of the plasma in a flaring coronal loop in which heat conduction is limited by turbulent scattering of the electrons that transport the thermal heat flux. The EBTEL equations are solved analytically in each of the two (conductiondominated and radiation-dominated) cooling phases. Comparison of the results with typical observed cooling times in solar flares shows that the turbulent mean free path lT lies in a range corresponding to a regime in which classical (collision-dominated) conduction plays at most a limited role. We also consider the magnitude and duration of the heat input that is necessary to account for the enhanced values of temperature and density at the beginning of the cooling phase and for the observed cooling times. We find through numerical modeling that in order to produce a peak temperature ≃ 1.5 x 10 ´7K and a 200 s cooling time consistent with observations, the flareheating profile must extend over a significant period of time; in particular, its lingering role must be taken into consideration in any description of the cooling phase. Comparison with observationally inferred values of postflare loop temperatures, densities, and cooling times thus leads to useful constraints on both the magnitude and duration of the magnetic energy release in the loop, as well as on the value of the turbulent mean free path λT.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Kontar, Dr Eduard and Bian, Dr Nicolas Horace
Authors: Bian, N., Emslie, A. G., Horne, D., and Kontar, E. P.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Astrophysical Journal
Publisher:IOP Publishing
ISSN:0004-637X
ISSN (Online):1538-4357
Published Online:15 January 2018
Copyright Holders:Copyright © 2018 The American Astronomical Society
First Published:First published in Astrophysical Journal 852(2): 127
Publisher Policy:Reproduced in accordance with the publisher copyright policy
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
631581Consolidated grant in solar and astrophysical plasmasLyndsay FletcherScience & Technology Facilities Council (STFC)ST/L000741/1S&E P&A - PHYSICS & ASTRONOMY