Forced oscillations of coronal loops driven by EIT waves
Forced oscillations of coronal loops driven by EIT waves
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DOI：
10.1051/0004-6361:200809833
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发表时间：
2008-07
影响因子：
6.5
通讯作者：
I. Ballai;M. Douglas;A. Marcu
中科院分区：
文献类型：
--
作者：
I. Ballai;M. Douglas;A. Marcu
目标。我们研究了在模拟全球日冕EIT波的外部驱动器的作用下，日冕环中横向振荡的产生，该环表示为一个直的薄通量管。我们调查如何产生的振荡取决于驱动程序的性质，以及两个系统之间的相互作用的类型。方法.我们考虑了一个固定端的磁性直圆柱体的振荡的影响下的外部驱动器建模的力量，由于全球EIT波。由于EIT波的性质的不确定性，我们首先近似的驱动程序的振荡力的时间，后来由一个有限宽度的冲击。结果结果表明，对于谐波驱动器，所产生的振荡的主导周期属于驱动器。根据驱动器的周期，与环路的自然周期相比，可以启动驻模谐波的混合。在非谐波驱动器（模拟冲击波）的情况下，回路中产生的振荡仅为固有周期。振荡的幅度由驱动器沿着管的位置决定。使用简单的数值方法实现所产生的振荡的全面诊断。
Aims. We study the generation of transversal oscillations in coronal loops represented as a straight thin flux tube under the effect of an external driver modelling the global coronal EIT wave. We investigate how the generated oscillations depend on the nature of the driver, and the type of interaction between the two systems. Methods. We consider the oscillations of a magnetic straight cylinder with fixed-ends under the influence of an external driver modelling the force due to the global EIT wave. Given the uncertainties related to the nature of EIT waves, we first approximate the driver by an oscillatory force in time and later by a shock with a finite width. Results. Results show that for a harmonic driver the dominant period in the generated oscillation belongs to the driver. Depending on the period of driver, compared to the natural periods of the loop, a mixture of standing modes harmonics can be initiated. In the case of a non-harmonic driver (modelling a shock wave), the generated oscillations in the loop are the natural periods only. The amplitude of oscillations is determined by the position of the driver along the tube. The full diagnosis of generated oscillations is achieved using simple numerical methods.