Self-Consistent Magnetohydrodynamic Modeling of a Coronal Mass Ejection, Coronal Dimming, and a Giant Cusp-shaped Arcade Formation
Self-Consistent Magnetohydrodynamic Modeling of a Coronal Mass Ejection, Coronal Dimming, and a Giant Cusp-shaped Arcade Formation
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DOI：
10.1086/496943
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发表时间：
2005-08
期刊：
影响因子：
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通讯作者：
D. Shiota;H. Isobe;P. Chen;Tetsuya T. Yamamoto;Takuma Sakajiri;K. Shibata
中科院分区：
文献类型：
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作者：
D. Shiota;H. Isobe;P. Chen;Tetsuya T. Yamamoto;Takuma Sakajiri;K. Shibata
我们对日冕物质抛射（CME）和相关的巨型拱廊结构进行了磁流体动力学模拟，结果提出了对日冕物质抛射观测的新解释。我们进行了两种模拟情况：有热传导和无热传导。比较两种情况的结果，我们发现导电情况下的重联率略高于绝热情况下的重联率，并且环路顶部的温度与横山-柴田标度定律预测的理论值一致。这两种情况下的速度和磁场等动力学特性相似，而温度和密度等热特性却截然不同。在这两种情况下，与磁重联相关的慢激波从重联区域沿着磁通绳周围的磁场线传播，并且激波前沿形成螺旋图案。就在慢激波之外，等离子体密度大大降低。将根据数值结果合成的软 X 射线图像与 Yohkoh 上的软 X 射线望远镜观测到的巨型拱廊的软 X 射线图像进行比较；通过模拟与观测的详细比较，证实了热传导的影响是显着的。合成和观察到的软 X 射线图像之间的比较为与日冕物质抛射和巨型拱廊相关的各种特征提供了新的解释。 (1) 1992年1月24日在巨型拱廊中观察到的Y形弹射结构很可能对应于与磁重联相关的慢速和快速冲击。 (2) 软X射线双调光对应于重联引起的稀疏。 (3) 调光区域的内边界对应于慢冲击。 (4) CME 的“三部分结构”可以用我们的数值结果来解释。 (5) 数值结果还表明，耀斑/巨型拱廊的骨干特征可能对应于向下重联流出碰撞形成的快速激波。
We performed magnetohydrodynamic simulations of coronal mass ejections (CMEs) and associated giant arcade formations, and the results suggest new interpretations of observations of CMEs. We performed two cases of the simulation: with and without heat conduction. Comparing between the results of the two cases, we found that the reconnection rate in the conductive case is a little higher than that in the adiabatic case and that the temperature of the loop top is consistent with the theoretical value predicted by the Yokoyama-Shibata scaling law. The dynamical properties such as velocity and magnetic field are similar in the two cases, whereas thermal properties such as temperature and density are very different. In both cases, slow shocks associated with magnetic reconnection propagate from the reconnection region along the magnetic field lines around the flux rope, and the shock fronts form spiral patterns. Just outside the slow shocks, the plasma density decreases greatly. The soft X-ray images synthesized from the numerical results are compared with the soft X-ray images of a giant arcade observed with the Soft X-Ray Telescope aboard Yohkoh; it is confirmed that the effect of heat conduction is significant for the detailed comparison between simulation and observation. The comparison between synthesized and observed soft X-ray images provides new interpretations of various features associated with CMEs and giant arcades. (1) It is likely that the Y-shaped ejecting structure, observed in the giant arcade on 1992 January 24, corresponds to slow and fast shocks associated with magnetic reconnection. (2) Soft X-ray twin dimming corresponds to the rarefaction induced by reconnection. (3) The inner boundary of the dimming region corresponds to the slow shocks. (4) The "three-part structure" of a CME can be explained by our numerical results. (5) The numerical results also suggest that a backbone feature of a flare/giant arcade may correspond to the fast shock formed by the collision of the downward reconnection outflow.