Numerical simulation of the internal plasma dynamics of post-flare loops

• Published in: Monthly notices of the Royal Astronomical Society Vol. 400; no. 4; pp. 1821 - 1828
• Main Authors: Fernández, C. A., Costa, A., Elaskar, S., Schulz, W.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 21-12-2009; Wiley-Blackwell; Oxford University Press
• Subjects: Astronomy; Astrophysics; Corona; Earth, ocean, space; Exact sciences and technology; Fluid mechanics; Magnetic fields; MHD; Numerical analysis; shock waves; Solar flares; Sun; Sun: activity; MHD; magnetic fields; Sun: activity; shock waves; Supersonic flow; Discontinuity; Magnetohydrodynamics; Slow shock wave; Flux tubes; Digital simulation; Adiabaticity; Brightening; Sun; Magnetoacoustic waves; Plasma dynamics; Two dimensional equation; Shock waves; Coronal loop; Energy equation; Plasma instability; Disturbances; Forcing; Magnetic fields
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1111/j.1365-2966.2009.15549.x

We integrate the magnetohydrodynamic (MHD) ideal equations of a slender flux tube to simulate the internal plasma dynamics of coronal post-flare loops. We study the onset and evolution of the internal plasma instability to compare with observations and to gain insight into physical processes and characteristic parameters associated with flaring events. The numerical approach uses a finite-volume Harten–Yee total variation diminishing scheme to integrate the one-dimensional 1/2 MHD equations specially designed to capture supersonic flow discontinuities. We could reproduce the observational sliding down and upwardly propagating of brightening features along magnetic threads of an event occurred on 2001 October 1. We show that high-speed downflow perturbations, usually interpreted as slow magnetoacoustic waves, could be better interpreted as slow magnetoacoustic shock waves. This result was obtained considering adiabaticity in the energy balance equation. However, a time-dependent forcing from the basis is needed to reproduce the reiteration of the event which resembles observational patterns – commonly known as quasi-periodic pulsations (QPPs)– which are related with large-scale characteristic longitudes of coherence. This result reinforces the interpretation that the QPPs are a response to the pulsational flaring activity.