2018/05/08 by Tongjiang Wang, L. Ofman, Leon Ofman +5
Biochemistry, Genetics and Molecular Biology · Physics and Astronomy · #Astrophysics #Computational physics #Coronal loop #Coronal mass ejection #Dissipation #Excitation #Extrapolation #Flare #Geomagnetism and Paleomagnetism Studies #Ionosphere and magnetosphere dynamics #Magnetic field #Magnetohydrodynamics #Mechanics #Nonlinear system #Optics #Physics #Solar and Space Plasma Dynamics #Solar wind #Standing wave #astro-ph.SR
paper · pdf · doi:10.3847/1538-4357/aac38a
19 pages, 17 figures,2 tables, 1 animation; accepted by ApJ
arxiv created 2018/05/08 · openalex publication_date 2018/06/18 · arxiv updated 2018/07/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract Standing slow-mode waves have been recently observed in flaring loops by the Atmospheric Imaging Assembly of the Solar Dynamics Observatory . By means of the coronal seismology technique, transport coefficients in hot (∼10 MK) plasma were determined by Wang et al., revealing that thermal conductivity is nearly suppressed and compressive viscosity is enhanced by more than an order of magnitude. In this study, we use 1D nonlinear MHD simulations to validate the predicted results from the linear theory and investigate the standing slow-mode wave excitation mechanism. We first explore the wave trigger based on the magnetic field extrapolation and flare emission features. Using a flow pulse driven at one footpoint, we simulate the wave excitation in two types of loop models: Model 1 with the classical transport coefficients and Model 2 with the seismology-determined transport coefficients. We find that Model 2 can form the standing wave pattern (within about one period) from initial propagating disturbances much faster than Model 1, in better agreement with the observations. Simulations of the harmonic waves and the Fourier decomposition analysis show that the scaling law between damping time ( τ ) and wave period ( P ) follows τ ∝ P 2 in Model 2, while τ ∝ P in Model 1. This indicates that the largely enhanced viscosity efficiently increases the dissipation of higher harmonic components, favoring the quick formation of the fundamental standing mode. Our study suggests that observational constraints on the transport coefficients are important in understanding both the wave excitation and damping mechanisms.