论文标题

线性背景旋转流对光球磁通管的磁声模式的影响

The effect of linear background rotational flows on magnetoacoustic modes of a photospheric magnetic flux tube

论文作者

Skirvin, Samuel, Fedun, Viktor, Silva, Suzana, Van Doorsselaere, Tom, Claes, Niels, Goossens, Marcel, Verth, Gary

论文摘要

太阳能磁通管中的磁声波可能会受到背景旋转流的存在的影响。在这里,我们调查了$ M = 0 $和$ M = \ pm的行为1 $模式的磁通管模式在有线性背景旋转流嵌入光谱环境中的情况下。我们表明,发现包含背景旋转流对轴对称$ M = 0 $香肠模式所获得的征量几乎没有影响。但是,扭结模式的解决方案取决于通过缓慢频率修改的流共振位置。背景旋转流使修改的流动共振在薄管(TT)限制中具有更快的相位速度$ m = 1 $。这导致了缓慢身体和慢速表面扭结模式的解决方案,以遵循这一轨迹,改变其分散行为。对于TT极限中的光球磁管,我们表明在比较其本本函数时很难区分慢速表面和快速表面扭结($ M = 1 $)模式。 2D速度场图证明了这些波在存在背景旋转流的存在下如何出现在观测数据中。对于缓慢的身体扭结模式,在总压力扰动中可以看到旋转模式。此外,管边界从方位角对称性的破裂中进行了螺旋运动,其中$ m = 1 $和$ m = -1 $模式变得不相相,这表明所得的扭结波是循环极化的。这些结果可能对太阳磁涡流中磁性流动波的地震学有意义。

Magnetoacoustic waves in solar magnetic flux tubes may be affected by the presence of background rotational flows. Here, we investigate the behaviour of $m=0$ and $m=\pm 1$ modes of a magnetic flux tube in the presence of linear background rotational flows embedded in a photospheric environment. We show that the inclusion of a background rotational flow is found to have little effect on the obtained eigensolutions for the axisymmetric $m=0$ sausage mode. However, solutions for the kink mode are dependent on the location of the flow resonance modified by the slow frequency. A background rotational flow causes the modified flow resonances to possess faster phase speeds in the thin-tube (TT) limit for the case $m=1$. This results in solutions for the slow body and slow surface kink modes to follow this trajectory, changing their dispersive behaviour. For a photospheric flux tube in the TT limit, we show that it becomes difficult to distinguish between the slow surface and fast surface kink ($m=1$) modes upon comparison of their eigenfunctions. 2D velocity field plots demonstrate how these waves, in the presence of background rotational flows, may appear in observational data. For slow body kink modes, a swirling pattern can be seen in the total pressure perturbation. Furthermore, the tube boundary undergoes a helical motion from the breaking of azimuthal symmetry, where the $m=1$ and $m=-1$ modes become out of phase, suggesting the resulting kink wave is circularly polarised. These results may have implications for seismology of magnetohydrodynamic waves in solar magnetic vortices.

扫码加入交流群

加入微信交流群

微信交流群二维码

扫码加入学术交流群,获取更多资源