标题： 大尺度前耀斑日冕电流片的重建与同型X形耀斑的相关性 显示英文标题

标题： Reconstruction of a Large-scale Pre-flare Coronal Current Sheet Associated with an Homologous X-shaped Flare

摘要： 作为太阳日冕中的基本磁结构，电流片（CSs）可能在太阳耀斑之前或期间形成，并通过磁重联使磁能耗散在太阳日冕中至关重要。 然而，静态的CS重建很少，可能是由于现有日冕磁场外推代码的内在限制。 在这里，我们使用SDO/HMI矢量磁图约束的MHD松弛模型，对太阳活动区11967中的大尺度前耀斑电流片进行了重建。 发现该电流片与一组特殊的同源耀斑有关，这些耀斑表现出独特的X形条带和环状结构，在四极磁配置中出现。 这一点得到了证实，即从电流片到光球的场线形成X形，几乎精确地再现了观测到的耀斑条带形状，表明耀斑是通过重联耗散电流片产生的。 电流片形成于一个双曲通量管中，这是两个准分离层的交集。 X形耀斑的重复可能归因于由光球足点运动驱动的电流片的重复形成和耗散。 这些结果展示了数据约束的MHD模型在再现日冕中的电流片以及提供太阳耀斑磁机制见解方面的强大能力。 显示英文摘要

摘要： As a fundamental magnetic structure in the solar corona, electric current sheets (CSs) can form either prior to or during solar flare, and they are essential for magnetic energy dissipation in the solar corona by enabling magnetic reconnection. However static reconstruction of CS is rare, possibly due to limitation inherent in available coronal field extrapolation codes. Here we present the reconstruction of a large-scale pre-flare CS in solar active region 11967 using an MHD-relaxation model constrained by SDO/HMI vector magnetogram. The CS is found to be associated with a set of peculiar homologous flares that exhibit unique X-shaped ribbons and loops occurring in a quadrupolar magnetic configuration. This is evidenced by that the field lines traced from the CS to the photosphere form an X shape which nearly precisely reproduces the shape of the observed flare ribbons, suggesting that the flare is a product of the dissipation of the CS through reconnection. The CS forms in a hyperbolic flux tube, which is an intersection of two quasi-separatrix layers. The recurrence of the X-shaped flares might be attributed to the repetitive formation and dissipation of the CS, as driven by the photospheric footpoint motions. These results demonstrate the power of data-constrained MHD model in reproducing CS in the corona as well as providing insight into the magnetic mechanism of solar flares.