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arXiv 1909.09787astro-ph.SR
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具有连续磁扭曲的日冕通量管中扭结振荡的共振吸收

Resonant absorption of kink oscillations in coronal flux tubes with continuous magnetic twist

Zanyar Ebrahimi, Karam Bahari

摘要:

日冕扭曲磁场的存在有观测证据。本文研究了磁通量管中磁流体动力学(MHD)扭折波的共振阻尼。考虑了具有连续磁扭转和径向非均匀密度分布的管的实际模型。利用线性MHD方程组在密度不均匀区外的解,通过与薄过渡层边界层上的解的适当联系,得到了扭折波的色散关系。研究了波浪的振荡频率和阻尼率与扭转参数和纵向波数的关系。对于本文所考虑的通量管参数,我们得到快速阻尼的扭结波的观测。为了证明这种快速阻尼的合理性,根据方位角扭结模式数的符号,$m=+1$或$m=-1$,背景磁场必须分别具有左手或右手扭曲轮廓。对于这里考虑的模型,共振吸收只发生在扭转参数是在由密度对比度指定的范围内。

英文摘要:

There are observational evidences for the existence of twisted magnetic field in the solar corona. Here, we have investigated resonant damping of the magnetohydrodynamic (MHD) kink waves in magnetic flux tubes. A realistic model of the tube with continuous magnetic twist and radially inhomogeneous density profile has been considered. We have obtained the dispersion relation of the kink wave using the solution to the linear MHD equations outside the density inhomogeneity and the appropriate connection formula to the solutions across the thin transitional boundary layer. The dependence of the oscillation frequency and damping rate of the waves on the twist parameter and longitudinal wavenumber has been investigated. For the flux tube parameters considered in this paper, we obtain rapid damping of the kink waves comparable to the observations. In order to justify this rapid damping, depending on the sign of the azimuthal kink mode number, $m=+1$ or $m=-1$, the background magnetic field must have left handed or right handed twisted profile, respectively. For the model considered here, the resonant absorption occurs only when the twist parameter is in a range specified by the density contrast.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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