Comparison of the Hall Magnetohydrodynamics and Magnetohydrodynamics Evolution of a Flaring Solar Active Region
Comparison of the Hall Magnetohydrodynamics and Magnetohydrodynamics Evolution of a Flaring Solar Active Region
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DOI：
10.3847/1538-4357/ac3bce
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发表时间：
2021-12
期刊：
影响因子：
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通讯作者：
K. Bora;R. Bhattacharyya;A. Prasad;B. Joshi;Q. Hu
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作者：
K. Bora;R. Bhattacharyya;A. Prasad;B. Joshi;Q. Hu
这项工作分析了霍尔磁流体力学(HMHD)和磁流体动力学(MHD)数值模拟的耀斑太阳活动区作为试验台，同时理想化的日冕阿尔芬速度小于两个数量级。与MHD相比，HMHD支持更快的磁重联，并且在磁力线演化方面显示出更丰富的复杂性。通过数值模拟和相关的多波长观测对引发耀斑的磁重联进行了探索。初始日冕磁场是由光球矢量磁场的无力外推构造的。耀斑所涉及的磁结构被确定为磁绳，其上覆的磁力线与三维零点和零线一起构成准分离线层(QSL)。与MHD模拟相比，HMHD模拟显示绳索的上升速度更高、速度更快，并与上面的场线一起，在位于日冕更高位置的QSL处进一步重新连接。场线的足点与HMHD事例的观测结果吻合得更好，耀斑带的中心部分位于色球。此外，在HMHD中发现场线以圆形图案旋转，而在MHD结果中没有看到这种旋转。有趣的是，还观察到等离子体在同空间色球区域内旋转，这使得HMHD模拟更可信。在上述协议的基础上，HMHD模拟被发现与观测结果更吻合，从而开辟了一条新的探索途径。
This work analyzes the Hall magnetohydrodynamics (HMHD) and magnetohydrodynamics (MHD) numerical simulations of a flaring solar active region as a test bed while idealizing the coronal Alfvén speed to be less by two orders of magnitude. HMHD supports faster magnetic reconnection and shows richer complexity in magnetic field line evolution compared to the MHD. The magnetic reconnections triggering the flare are explored by numerical simulations augmented with relevant multiwavelength observations. The initial coronal magnetic field is constructed by non-force-free extrapolation of photospheric vector magnetic field. Magnetic structure involved in the flare is identified to be a flux rope, with its overlying magnetic field lines constituting the quasi-separatrix layers (QSLs) along with a three-dimensional null point and a null line. Compared to the MHD simulation, the HMHD simulation shows a higher and faster ascent of the rope together with the overlying field lines, which further reconnect at the QSL located higher up in the corona. The footpoints of the field lines match better with the observations for the HMHD case, with the central part of the flare ribbon located at the chromosphere. Additionally, field lines are found to rotate in a circular pattern in the HMHD, whereas no such rotation is seen in the MHD results. Interestingly, plasma is also observed to be rotating in a cospatial chromospheric region, which makes the HMHD simulation more credible. Based on the aforementioned agreements, HMHD simulation is found to agree better with observations and thus opens up a novel avenue to explore.