Coronal Electric Currents and Kink Instability of Magnetic Flux Rope

IF 2.7 3区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

Solar Physics Pub Date : 2025-04-03 DOI:10.1007/s11207-025-02461-9

Yuriy T. Tsap, Alexander V. Stepanov, Yulia G. Kopylova

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Abstract

Using the energy method and the thin magnetic flux tube approximation, we find the wave dispersion relation for magnetohydrodynamic kink oscillations of a force-free magnetic flux rope with uncompensated longitudinal electric current under solar coronal conditions. The eigenvectors are shown to impose restrictions on the conditions of the kink instability of a flux rope. The observed weak twist of coronal loops with a small (\(\lesssim 1\)) number of turns of the magnetic field lines around the axis indicates the dominance of unshielded magnetic flux ropes in the corona of the Sun, in which the longitudinal electric currents do not exceed \(10^{11}\) – \(10^{12}\) A. These restrictions can be associated with the absence of solar superflares. The period of kink oscillations of twisted coronal loops should decrease with decreasing longitudinal electric current, which can be used to study its dynamics in solar flares. No dependence of compact and eruptive solar flares on the twist of flux ropes can be explained by the coexistence of both shielded and unshielded electric currents in the corona.

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磁通绳的日冕电流与扭结不稳定性

利用能量法和薄磁通管近似，得到了日冕条件下无力磁通绳无补偿纵向电流的磁流体动力学扭结振荡的波频散关系。本征向量对磁通绳扭结不稳定性的条件施加了限制。观测到的日冕环的微弱扭曲与绕轴磁场线的小（\(\lesssim 1\)）圈数表明，在太阳日冕中，未屏蔽的磁通绳占主导地位，其中的纵向电流不超过\(10^{11}\) - \(10^{12}\) a .这些限制可能与太阳超级耀斑的缺失有关。扭曲日冕环的扭结振荡周期应随纵向电流的减小而减小，这可用于研究其在太阳耀斑中的动力学。紧凑的和爆发的太阳耀斑不依赖于通量绳的扭曲，这可以用日冕中屏蔽和非屏蔽电流的共存来解释。

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来源期刊

Solar Physics 地学天文-天文与天体物理

CiteScore

5.10

自引率

17.90%

发文量

146

审稿时长

1 months

期刊介绍： Solar Physics was founded in 1967 and is the principal journal for the publication of the results of fundamental research on the Sun. The journal treats all aspects of solar physics, ranging from the internal structure of the Sun and its evolution to the outer corona and solar wind in interplanetary space. Papers on solar-terrestrial physics and on stellar research are also published when their results have a direct bearing on our understanding of the Sun.