Kink Oscillation of a Flux Rope During a Failed Solar Eruption

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 Å, 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 Alfvén 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.

11 pages, 7 figures, ApJ Letters (in press)

References in corpus (9)

• Thermal Diagnostics with the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory: A Validated Method for Differential Emission Measure Inversions
• Coronal heating by MHD waves
• Kink oscillations of coronal loops
• Large amplitude oscillation of a polar crown filament in the pre-eruption phase
• 3D Radio and X-Ray Modeling and Data Analysis Software: Revealing Flare Complexity
• Large-Amplitude Oscillation of an Erupting Filament as Seen in EUV, H-alpha and Microwave Observations
• Excitation of decay-less transverse oscillations of coronal loops by random motions
• Generating transverse loop oscillations through a steady-flow driver
• Magneto-Acoustic Waves in Magnetic Twisted Flux Tube

Cited by in corpus (2)

• Plasmoids, Flows, and Jets During Magnetic Reconnection in a Failed Solar Eruption
• Failed Solar Eruption of A Multi-thermal Flux Rope