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

andrea costa   Submitted: 2009-10-02 17:20

We integrate the 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- 1 volume Harten-Yee TVD scheme to integrate the 1D 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 October 1st, 2001. 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. How- ever, 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.

Authors: Fernández, Carlos, Costa, Andrea, Elaskar, Sergio, Schulz, Walkiria
Projects: TRACE

Publication Status: Accepted MNRAS
Last Modified: 2009-10-05 09:41
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Numerical simulation of dark lanes in post-flare supra-arcade  

andrea costa   Submitted: 2009-10-02 17:14

We integrate the MHD ideal equations to simulate dark void sun wardly moving structures in post-flare supra-arcades. We study the onset and evolution of the internal plasma instability tocompare with observations and to gain insight into physical processes and characteristic parametersof these phenomena. The numerical approach uses a finite-volume Harten-Yee TVD scheme to integrate the 1D½ MHD equations specially designed to capture supersonic flow discontinuities.The integration is performed in both directions, the sunward radial one and the transverse to themagnetic field. For the first time, we numerically reproduce observational dark voids describedin Verwichte et al. (2005). We show that the dark tracks are plasma vacuums generated by thebouncing and interfering of shocks and expansion waves, upstream an initial slow magnetoacousticshock produced by a localized deposition of energy modeled with a pressure perturbation. The samepressure perturbation produces a transverse to the field or perpendicular magnetic shock giving riseto nonlinear waves that compose the kink-like plasma void structures, with the same functionalsunward decreasing phase speed and constancy with height of the period, as those determined bythe observations.

Authors: Costa, Andrea, Elaskar, Sergio, Fernández, Carlos, Martínez, Guadalupe
Projects: TRACE

Publication Status: Accepted MNRAS
Last Modified: 2009-10-05 09:42
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Numerical simulation of the internal plasma dynamics of post-flare loops
Numerical simulation of dark lanes in post-flare supra-arcade

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