Determination of Transport Coefficients by Coronal Seismology of Flare-induced Slow-mode Waves: Numerical Parametric Study of a 1D Loop Model

• Published in: The Astrophysical journal 2019-11, Vol.886 (1), p.2
• Main Authors: Wang, Tongjiang, Ofman, Leon
• Format: Article
• Language: English
• Subjects: Active solar corona; Astrophysics; Atmospheric models; Computational fluid dynamics; Computer simulation; Conduction; Helioseismology; Magnetic properties; Magnetoacoustic waves; Magnetohydrodynamics; Mathematical models; Parametric statistics; Physical properties; Seismology; Solar activity; Solar coronal loops; Solar coronal seismology; Solar coronal waves; Solar extreme ultraviolet emission; Solar flares; Solar observatories; Standing waves; Thermal conductivity; Transport properties; Viscosity; Viscosity coefficient
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ab478f

Recent studies of a flaring loop oscillation event on 2013 December 28 observed by the Atmospheric Imaging Assembly of the Solar Dynamics Observatory have revealed the suppression of thermal conduction and significant enhancement of compressive viscosity in hot (∼10 MK) plasma. In this study we aim at developing a new coronal seismology method for determining the transport coefficients based on a parametric study of wave properties using a 1D nonlinear magnetohydrodynamics (MHD) loop model in combination with the linear theory. The simulations suggest a two-step scheme: we first determine the effective thermal conduction coefficient from the observed phase shift between temperature and density perturbations as this physical parameter is insensitive to the unknown viscosity; then from the loop model with the obtained thermal conduction coefficient, we determine the effective viscosity coefficient from the observed decay time using the parametric modeling. With this new seismology technique we are able to quantify the suppression of thermal conductivity by a factor of about 3 and the enhancement of viscosity coefficient by a factor of 10 in the studied flaring loop. Using the loop model with these refined transport coefficients, we study the excitation of slow magnetoacoustic waves by launching a flow pulse from one footpoint. The simulation can self-consistently produce the fundamental standing wave on a timescale in agreement with the observation.