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arXiv · 2205.03480

Kink Oscillation of a Flux Rope During a Failed Solar Eruption

Pankaj Kumar·Valery M. Nakariakov·Judith T. Karpen·C. Richard DeVore·Kyung-Suk Cho
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Abstract

We report a decaying kink oscillation of a flux rope during a confined eruptive flare, observed off the solar limb by SDO/AIA, that lacked a detectable white-light coronal mass ejection. The erupting flux rope underwent kinking, rotation, and apparent leg-leg interaction during the event. The oscillations were observed simultaneously in multiple AIA channels at 304, 171, and 193 {\AA}, indicating that multithermal plasma was entrained in the rope. After reaching the overlying loops in the active region, the flux rope exhibited large-amplitude, decaying kink oscillations with an apparent initial amplitude of 30 Mm, period of about 16 min, and decay time of about 17 min. We interpret these oscillations as a fundamental standing kink mode of the flux rope. The oscillation polarization has a clear vertical component, while the departure of the detected waveform from a sinusoidal signal suggests that the oscillation could be circularly or elliptically polarized. The estimated kink speed is 1080 km/s, corresponding to an Alfv\'en speed of about 760 km/s. This speed, together with the estimated electron density in the rope from our DEM analysis, $n_e \approx$(1.5--2.0)$\times 10^9$cm$^{-3}$, yields a magnetic field strength of about 15 G. To the best of our knowledge, decaying kink oscillations of a flux rope with non-horizontal polarization during a confined eruptive flare have not been reported before. These oscillations provide unique opportunities for indirect measurements of the magnetic-field strength in low-coronal flux ropes during failed eruptions.

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Pankaj Kumar, Valery M. Nakariakov, Judith T. Karpen, C. Richard DeVore, Kyung-Suk Cho. 2022-05-06. Kink Oscillation of a Flux Rope During a Failed Solar Eruption. https://doi.org/10.3847/2041-8213%2Fac6e3e

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