Decay-less kink oscillations in coronal loops
Decay-less kink oscillations in coronal loops
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DOI：
10.1051/0004-6361/201322094
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发表时间：
2013-12-01
影响因子：
6.5
通讯作者：
Nakariakov, V. M.
中科院分区：
文献类型：
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作者：
Anfinogentov, S.;Nistico, G.;Nakariakov, V. M.
上下文。利用太阳动力学观测站(SDO)的成像组件阵列(AIA)仪器在171埃处探测到了日冕环在非肢体活动区的扭结振荡。我们的目标是测量不同环路扭结振荡的周期和幅度，并确定振荡相位沿振荡环路的演化。在SDO/AIA和STEREO/EUVI-A的视野中直观地识别出振荡的冠状环：通过三维分析得出环的长度。几个狭缝沿着环路被用来组装时间距离图。我们确定了振荡模式，并恢复了振荡的周期和幅度。我们应用互相关技术来估计振荡环不同部分的振荡之间的相移。我们发现，所有被分析的回路都显示出低幅度的无衰减横向振荡。同一活动区内的环路振荡周期为2.5~11min，不同环路的振荡周期不同。位移幅度小于1 mm。沿着每个被分析的回路，振荡相位是恒定的。振荡位相的空间结构对应于基本的驻留扭结模。我们得出的结论是，对于受非共振连续工作外力影响的阻尼谐振子，观察到的行为与经验模型是一致的。
Context. Kink oscillations of coronal loops in an off-limb active region are detected with the Imaging Assembly Array (AIA) instruments of the Solar Dynamics Observatory (SDO) at 171 angstrom.Aims. We aim to measure periods and amplitudes of kink oscillations of different loops and to determinate the evolution of the oscillation phase along the oscillating loop.Methods. Oscillating coronal loops were visually identified in the field of view of SDO/AIA and STEREO/EUVI-A: the loop length was derived by three-dimensional analysis. Several slits were taken along the loops to assemble time-distance maps. We identified oscillatory patterns and retrieved periods and amplitudes of the oscillations. We applied the cross-correlation technique to estimate the phase shift between oscillations at different segments of oscillating loops.Results. We found that all analysed loops show low-amplitude undamped transverse oscillations. Oscillation periods of loops in the same active region range from 2.5 to 11 min, and are different for different loops. The displacement amplitude is lower than 1 Mm. The oscillation phase is constant along each analysed loop. The spatial structure of the phase of the oscillations corresponds to the fundamental standing kink mode. We conclude that the observed behaviour is consistent with the empirical model in terms of a damped harmonic resonator affected by a non-resonant continuously operating external force.