Magnetohydrodynamic Wave Modes of Solar Magnetic Flux Tubes with an Elliptical Cross Section
Magnetohydrodynamic Wave Modes of Solar Magnetic Flux Tubes with an Elliptical Cross Section
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DOI：
10.3847/1538-4357/abec7a
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发表时间：
2021-05
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影响因子：
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通讯作者：
A. Aldhafeeri;G. Verth;W. Brevis;D. Jess;M. McMurdo;V. Fedun
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文献类型：
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作者：
A. Aldhafeeri;G. Verth;W. Brevis;D. Jess;M. McMurdo;V. Fedun
本文的目的是研究磁环境中椭圆截面可压缩磁通管中传播的磁流体(MHD)波模式的行为。数值求解了描述椭圆形磁通管中允许的MHD波模行为的色散关系。我们考虑了著名的圆形通量管模型中纯实本征模的空间结构的扭曲。它已经在光球和日冕条件下进行了研究。结果表明：(I)偶Mathieu函数形式的解比奇Mathieu函数形式的解对偏心率的大小更敏感；(Ii)如果磁通管截面的椭圆度增加，香肠模式(m=0)很难识别；(Iii)对应于凹槽模式(m=3)的偶数解由于它们的相似性而被误解为扭结模式(m=1)。与沿长轴极化并强烈依赖于磁通管椭圆度的凹槽模式不同，扭结模式和香肠表面模式几乎不受椭圆度的影响。给出了气孔和太阳黑子中允许的本征模空间结构的几个例子。在柱对称近似下得到的解与前人的研究结果一致。
The purpose of this paper is to study the behavior of magnetohydrodynamic (MHD) wave modes that propagate in compressible magnetic flux tubes with an elliptical cross section embedded in a magnetic environment. The dispersion relation that describes the behavior of MHD wave modes permitted in an elliptical magnetic flux tube is solved numerically. Distortion of the spatial structure of the purely real eigenmodes from the well-known circular flux tube model has been considered. It has been studied under both photospheric and coronal conditions. It has been shown that (i) solutions in the form of even Mathieu functions are more sensitive to the value of eccentricity than solutions with the form of odd Mathieu functions; (ii) if the ellipticity of the cross section of the magnetic flux tube increases, a sausage mode (m = 0) cannot be easily identified; (iii) even solutions that correspond to the fluting mode (m = 3) can be misinterpreted as a kink mode (m = 1) due to their similarities. In contrast to the fluting modes that are polarized along the major axis and strongly depend on the ellipticity of the magnetic flux tube, the kink and sausage surface modes are practically unaffected by ellipticity. Several examples of the spatial structure of the eigenmodes permitted in the pores and sunspots have been visualized. The solutions obtained in the approximation of cylindrical symmetry are in agreement with previous studies.