Transverse Coronal-Loop Oscillations Induced by the Non-radial Eruption of a Magnetic Flux Rope

We investigate the transverse coronal-loop oscillations induced by the eruption of a prominence-carrying flux rope on 7 December 2012. The flux rope, originating from NOAA Active Region (AR) 11621, was observed in extreme-ultraviolet (EUV) wavelengths by the Atmospheric Imaging Assembly (AIA) onboar...

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Bibliographic Details
Published in:	Solar physics 2022-02, Vol.297 (2), Article 18
Main Authors:	Zhang, Q. M., Chen, J. L., Li, S. T., Lu, L., Li, D.
Format:	Article
Language:	eng
Subjects:	Amplitudes Astrophysics and Astroparticles Atmospheric Sciences Coronal loops Damping Eruptions Fluctuations Helioseismology Horizontal orientation Magnetic flux Magnetohydrodynamic (MHD) Waves and Oscillations in the Sun’s Corona and MHD Coronal Seismology Observatories Physics Physics and Astronomy Prominences Seismology Solar activity Solar observatories Solar physics Space Exploration and Astronautics Space Sciences (including Extraterrestrial Physics Spacecraft Vertical oscillations Wavelengths
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Summary:	We investigate the transverse coronal-loop oscillations induced by the eruption of a prominence-carrying flux rope on 7 December 2012. The flux rope, originating from NOAA Active Region (AR) 11621, was observed in extreme-ultraviolet (EUV) wavelengths by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) spacecraft and in the H α line center by the ground-based telescope at the Big Bear Solar Observatory (BBSO). The early evolution of the flux rope is divided into two steps: a slow-rise phase at a speed of ≈ 230 km s −1 and a fast-rise phase at a speed of ≈ 706 km s −1 . The eruption generates a C5.8 flare and the onset of the fast rise is consistent with the hard X-ray (HXR) peak time of the flare. The embedded prominence has a lower speed of ≈ 452 km s −1 . The eruption is significantly inclined from the local solar normal by ≈ 60 ∘ , suggesting a typical non-radial eruption. During the early eruption of the flux rope, the nearby coronal loops are disturbed and experience independent kink-mode oscillations in the horizontal and vertical directions. The oscillation in the horizontal direction has an initial amplitude of ≈ 3.1 Mm, a period of ≈ 294 seconds, and a damping time of ≈ 645 seconds. It is most striking in 171 Å and lasts for three to four cycles. The oscillations in the vertical directions are observed mainly in 171, 193, and 211 Å. The initial amplitudes are in the range of 3.4 – 5.2 Mm, with an average value of 4.5 Mm. The periods are between 407 seconds and 441 seconds, with an average value of 423 seconds. The oscillations are damping and last for nearly four cycles. The damping times are in the range of 570 – 1012 seconds, with an average value of 741 seconds. Assuming a semi-circular shape of the vertically oscillating loops, we calculate the loop lengths according to their heights. Using the observed periods, we carry out coronal seismology and estimate the internal Alfvén speeds (988 – 1145 km s −1 ) and the magnetic-field strengths (12 – 43 G) of the oscillating loops.
ISSN:	0038-0938 1573-093X