MAGNETOHYDRODYNAMIC SHOCKS IN AND ABOVE POST-FLARE LOOPS: TWO-DIMENSIONAL SIMULATION AND A SIMPLIFIED MODEL
MAGNETOHYDRODYNAMIC SHOCKS IN AND ABOVE POST-FLARE LOOPS: TWO-DIMENSIONAL SIMULATION AND A SIMPLIFIED MODEL
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DOI：
10.1088/0004-637x/805/2/135
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发表时间：
2015-04
期刊：
影响因子：
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通讯作者：
S. Takasao;Takuma Matsumoto;N. Nakamura;K. Shibata
中科院分区：
文献类型：
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作者：
S. Takasao;Takuma Matsumoto;N. Nakamura;K. Shibata
太阳耀斑是一种爆炸现象，在耀斑后的环内和环上方预计会出现超音速流动和冲击。为了了解耀斑后环的动力学，对太阳耀斑进行了二维磁流体动力学（2D MHD）模拟。我们发现了新的冲击波结构和以上的耀斑后环，这是没有解决的，在以前的工作由Yokoyama和柴田。为了研究沿着重联磁场流动的动力学，沿着选定的场线研究等离子体的运动学和能量学。研究发现，激波是决定耀斑后环的热结构和流结构的关键。在二维MHD模拟的基础上，我们发展了一个新的耀斑后环模型，即伪二维MHD模型。该模型是基于一维（1D）MHD方程，其中所有变量依赖于一个空间维度，并考虑所有的磁场和速度场的三个分量。我们的伪二维模型包括了许多与磁重联（特别是MHD冲击）有关的多维MHD过程的特征，这些特征是以前的一维流体动力学模型所不能包括的。我们比较了二维计算和伪二维MHD模型中的激波形成和能量学，发现它们给出了相似的结果。这个模型将使我们能够在一个广泛的参数空间中研究耀斑后环的演化，而不会产生昂贵的计算成本或忽略与磁重联相关的重要物理。
Solar flares are an explosive phenomenon where super-sonic flows and shocks are expected in and above the post-flare loops. To understand the dynamics of post-flare loops, a two-dimensional magnetohydrodynamic (2D MHD) simulation of a solar flare has been carried out. We found new shock structures in and above the post-flare loops, which were not resolved in the previous work by Yokoyama & Shibata. To study the dynamics of flows along the reconnected magnetic field, the kinematics and energetics of the plasma are investigated along selected field lines. It is found that shocks are crucial to determine the thermal and flow structures in the post-flare loops. On the basis of the 2D MHD simulation, we developed a new post-flare loop model, which we defined as the pseudo-2D MHD model. The model is based on the one-dimensional (1D) MHD equations, where all variables depend on one space dimension, and all the three components of the magnetic and velocity fields are considered. Our pseudo-2D model includes many features of the multi-dimensional MHD processes related to magnetic reconnection (particularly MHD shocks), which the previous 1D hydrodynamic models are not able to include. We compared the shock formation and energetics of a specific field line in the 2D calculation with those in our pseudo-2D MHD model, and found that they give similar results. This model will allow us to study the evolution of the post-flare loops in a wide parameter space without expensive computational cost or neglecting important physics associated with magnetic reconnection.