一个持续的宁静太阳小规模龙卷风。II。振荡
A persistent quiet-Sun small-scale tornado. II. Oscillations
摘要：
最近，一个持续的1.7小时的涡流，类似于一个小规模的龙卷风的特性和动力学进行了研究与地面和空间为基础的观测，并首次在Ha线中心。涡流表现出显着的亚结构的形式，几个间歇色球漩涡。我们调查的各种物理参数在涡流区的振荡行为，在涡流区和安静的太阳区域（比较）内进行的二维小波分析，使用相同的高空间和时间分辨率哈和钙II 8542 CRISP观测，以及多普勒速度和半高宽来自哈线轮廓。涡流在3-5分钟范围内显示出显著的振荡功率，在4分钟左右达到峰值，并且与参考安静太阳区域的行为不同。振荡反映了不同分量的累积作用，如摇摆运动、旋转和波浪。结果表明，摇摆运动周期在200-220 s之间，自转周期为270 s左右（Ha）和215 s左右（Ca Ⅱ）。周期随着大气高度的增加而增加，似乎随着离涡旋中心的径向距离而减少，这表明偏离了刚性旋转。作为周期和高度的函数的涡流内的功率的行为意味着倏逝波的存在和不同类型的波的激发，例如磁声（例如扭结）或阿尔芬波。涡流似乎是由两个运动：横向（摇摆）运动，和旋转运动，而振荡点内的波的传播。附近的纤维状流可能在涡流的旋转调制中发挥重要作用。间接证据表明，该结构是磁性支撑的，而中心漩涡似乎是作为一个“中央发动机”的涡流。
英文摘要：
Recently, the characteristics, and dynamics of a persistent 1.7 h vortex flow, resembling a small-scale tornado, have been investigated with ground-base and space-based observations and for the first time in the Ha line centre. The vortex flow showed significant substructure in the form of several intermittent chromospheric swirls. We investigate the oscillatory behaviour of various physical parameters in the vortex area, with a 2D wavelet analysis performed within the vortex flow area and in a quiet-Sun region (for comparison), using the same high spatial and temporal resolution Ha and Ca II 8542 CRISP observations, as well as Doppler velocities and FWHM derived from the Ha line profiles. The vortex flow shows significant oscillatory power in the 3-5 min range that peaks around 4 min and behaves differently than the reference quiet-Sun region. Oscillations reflect the cumulative action of different components such as swaying motions, rotation, and waves. The derived swaying motion periods are in the range of 200-220 s, and the rotation periods are ~270 s for Ha and ~215 s for Ca II. Periods increase with atmospheric height and seem to decrease with radial distance from the vortex centre, suggesting a deviation from a rigid rotation. The behaviour of power within the vortex flow as a function of period and height implies the existence of evanescent waves and the excitation of different types of waves, such as magnetoacoustic (e.g. kink) or Alfven waves. The vortex flow seems to be dominated by two motions: a transverse (swaying) motion, and a rotational motion while oscillations point to the propagation of waves within it. Nearby fibril-like flows could play an important role in the rotational modulation of the vortex flow. Indirect evidence exists that the structure is magnetically supported while the central swirl seems to be acting as a "central engine" to the vortex flow.
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