Studying the Transfer of Magnetic Helicity in Solar Active Regions with the Connectivity-based Helicity Flux Density Method
Studying the Transfer of Magnetic Helicity in Solar Active Regions with the Connectivity-based Helicity Flux Density Method
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DOI：
10.3847/1538-4357/aaa1e1
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发表时间：
2017-07
期刊：
影响因子：
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通讯作者：
K. Dalmasse;E. Pariat;G. Valori;Ju Jing;P. Démoulin
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文献类型：
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作者：
K. Dalmasse;E. Pariat;G. Valori;Ju Jing;P. Démoulin
在日冕中，磁螺旋度缓慢而持续地积累，以响应等离子体流切向光球和磁通量出现通过它。分析这种转移的磁螺旋度是关键，以确定其在活动区（AR）的动力学作用。基于连通性的螺旋度通量密度方法是近年来发展起来的研究AR中磁螺旋度的二维和三维传输的方法。该方法考虑到磁螺旋度的3D性质，明确使用的磁场连通性的知识，这使得它能够忠实地跟踪磁螺旋度的光球通量。由于磁场在日冕中没有测量，因此必须使用从无力磁场外推获得的建模3D解决方案来导出磁连接性。不同的外推方法可以导致明显不同的三维磁场连通性，从而质疑的可靠性的连通性为基础的方法在观测应用。我们解决这些问题，通过将这种方法应用到孤立的和内部复杂的AR 11158与不同的磁场外推模型。我们表明，基于连通性的计算是强大的不同的外推方法，特别是在识别区域的相反的磁螺旋通量。我们的结论是，基于连通性的方法可以可靠地用于观测分析，是一个很有前途的工具，用于研究转移的磁螺旋在AR的，并将其与他们的耀斑活动。
In the solar corona, magnetic helicity slowly and continuously accumulates in response to plasma flows tangential to the photosphere and magnetic flux emergence through it. Analyzing this transfer of magnetic helicity is key for identifying its role in the dynamics of active regions (ARs). The connectivity-based helicity flux density method was recently developed for studying the 2D and 3D transfer of magnetic helicity in ARs. The method takes into account the 3D nature of magnetic helicity by explicitly using knowledge of the magnetic field connectivity, which allows it to faithfully track the photospheric flux of magnetic helicity. Because the magnetic field is not measured in the solar corona, modeled 3D solutions obtained from force-free magnetic field extrapolations must be used to derive the magnetic connectivity. Different extrapolation methods can lead to markedly different 3D magnetic field connectivities, thus questioning the reliability of the connectivity-based approach in observational applications. We address these concerns by applying this method to the isolated and internally complex AR 11158 with different magnetic field extrapolation models. We show that the connectivity-based calculations are robust to different extrapolation methods, in particular with regard to identifying regions of opposite magnetic helicity flux. We conclude that the connectivity-based approach can be reliably used in observational analyses and is a promising tool for studying the transfer of magnetic helicity in ARs and relating it to their flaring activity.