Volume 625, May 2019
|Number of page(s)||14|
|Published online||29 May 2019|
The effects of numerical resolution, heating timescales and background heating on thermal non-equilibrium in coronal loops
School of Mathematics and Statistics, University of St Andrews, St Andrews, Fife KY16 9SS, UK
2 Space and Atmospheric Physics, The Blackett Laboratory, Imperial College, London SW7 2BW, UK
3 Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA
Accepted: 10 April 2019
Thermal non-equilibrium (TNE) is believed to be a potentially important process in understanding some properties of the magnetically closed solar corona. Through one-dimensional hydrodynamic models, this paper addresses the importance of the numerical spatial resolution, footpoint heating timescales and background heating on TNE. Inadequate transition region (TR) resolution can lead to significant discrepancies in TNE cycle behaviour, with TNE being suppressed in under-resolved loops. A convergence on the periodicity and plasma properties associated with TNE required spatial resolutions of less than 2 km for a loop of length 180 Mm. These numerical problems can be resolved using an approximate method that models the TR as a discontinuity using a jump condition, as proposed by Johnston et al. (2017a, A&A, 597, A81; 2017b, A&A, 605, A8). The resolution requirements (and so computational cost) are greatly reduced while retaining good agreement with fully resolved results. Using this approximate method we (i) identify different regimes for the response of coronal loops to time-dependent footpoint heating including one where TNE does not arise and (ii) demonstrate that TNE in a loop with footpoint heating is suppressed unless the background heating is sufficiently small. The implications for the generality of TNE are discussed.
Key words: Sun: corona / Sun: magnetic fields / magnetohydrodynamics (MHD) / hydrodynamics / Sun: transition region / Sun: oscillations
© ESO 2019
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.