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arXiv 0909.5600astro-ph.SR
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耀斑后超拱廊暗巷的数值模拟

Numerical simulation of dark lanes in post-flare supra-arcade

A. Costa, S. Elaskar, C. Fernandez, G. Martinez

摘要:

我们整合MHD理想方程来模拟耀斑后拱廊上的暗空洞向日移动结构。我们研究了内部等离子体不稳定性的发生和演化,与观测结果进行比较,并深入了解这些现象的物理过程和特征参数。数值方法采用有限体积Harten-Yee TVD格式积分一维1/2 MHD方程,该方程是专门为捕捉超音速流动间断而设计的。积分是在两个方向上进行的,即向阳的径向方向和磁场的横向方向。这是第一次,我们数值再现了Verwichte等人(2005)中描述的观测暗空洞。我们发现,黑暗的轨道是由反弹和干扰的冲击和膨胀波产生的等离子体真空,上游的初始缓慢磁声冲击产生的局部沉积的能量建模与压力扰动。相同的压力扰动产生横向的磁场或垂直的磁冲击引起的非线性波组成的扭结状等离子体空隙结构,具有相同的功能向阳下降的相速度和恒定性与高度的周期,由观测确定。

英文摘要:

We integrate the MHD ideal equations to simulate dark void sunwardly moving structures in post--flare supra--arcades. 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 of these phenomena. The numerical approach uses a finite-volume Harten-Yee TVD scheme to integrate the 1D1/2 MHD equations specially designed to capture supersonic flow discontinuities. The integration is performed in both directions, the sunward radial one and the transverse to the magnetic field. For the first time, we numerically reproduce observational dark voids described in Verwichte et al. (2005). We show that the dark tracks are plasma vacuums generated by the bouncing and interfering of shocks and expansion waves, upstream an initial slow magnetoacoustic shock produced by a localized deposition of energy modeled with a pressure perturbation. The same pressure perturbation produces a transverse to the field or perpendicular magnetic shock giving rise to nonlinear waves that compose the kink--like plasma void structures, with the same functional sunward decreasing phase speed and constancy with height of the period, as those determined by the observations.

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