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Journal Paper

전체
Oscillation of a Small Hα Surge in a Solar Polar Coronal Hole SCI
  • Cho Kyungsuk;Il-Hyun Cho;V. M. Nakariakov;Vasyl B. Yurchyshyn;Heesu Yang;Kim Yeon-Han;Pankaj Kumar;Tetsuya Magara
  • 2019-05-20
  • ASTROPHYSICAL JOURNAL LETTERS 877 1 : L1-1~L1-7
Hα surges (i.e., cool/dense collimated plasma ejections) may act as a guide for a propagation of magnetohydrodynamic waves. We report a high-resolution observation of a surge observed with 1.6 m Goode Solar Telescope (GST) on 2009 August 26, from 18:20 UT to 18:45 UT. Characteristics of plasma motions in the surge are determined with the normalizing radial gradient filter and the Fourier motion filter. The shape of the surge is found to change from a "C" shape to an inverse "C" shape after a formation of a cusp, a signature of reconnection. There are apparent upflows seen above the cusp top and downflows below it. The upflows show rising and rotational motions in the right-hand direction, with the rotational speed decreasing with height. Near the cusp top, we find a transverse oscillation of the surge, with the period of ~2 minutes. There is no change of the oscillation phase below the cusp top, but above the top a phase change is identified, giving a vertical phase speed about 86 km s?1. As the height increases, the initial amplitude of the oscillation increases, and the oscillation damping time decreases from 5.13 to 1.18 minutes. We conclude that the oscillation is a propagating kink wave that is possibly excited by the repetitive spontaneous magnetic reconnection.