First Detection of Transverse Vertical Oscillation during the Expansion of Coronal Loops

Abstract

In this Letter, we perform a detailed analysis of the M5.5 class eruptive flare occurring in active region 12,929 on 2022 January 20. The eruption of a hot channel generates a fast coronal mass ejection (CME) and a dome-shaped extreme-ultraviolet (EUV) wave at speeds of 740–860 km s−1. The CME is associated with a type II radio burst, implying that the EUV wave is a fast-mode shock wave. During the impulsive phase, the flare shows quasi-periodic pulsations (QPPs) in EUV, hard X-ray, and radio wavelengths. The periods of QPPs range from 18 to 113 s, indicating that flare energy is released and nonthermal electrons are accelerated intermittently with multiple timescales. The interaction between the EUV wave and low-lying adjacent coronal loops (ACLs) results in contraction, expansion, and transverse vertical oscillation of ACLs. The speed of contraction in 171, 193, and 211 Å is higher than that in 304 Å. The periods of oscillation are 253 s and 275 s in 304 Å and 171 Å, respectively. A new scenario is proposed to explain the interaction. The equation that interprets the contraction and oscillation of the overlying coronal loops above a flare core can also interpret the expansion and oscillation of ACLs, suggesting that the two phenomena are the same in essence.

Numerical Simulations of Oscillations in Solar Corona Excited by Vortex Shedding

“…This leads to several possible processes that can excite transverse oscillations of loops in the solar atmosphere by the vortex shedding: (a) loops (rope) ejected during CMEs and penetrating into the static plasma in front of CMEs, (b) loops ejected during CMEs, but with a slower velocity than that of surrounding CME plasma, (c) rapidly shrinking loops after flares and CMEs, and (d) static loops in plasma flows from surrounding flares and CMEs. Among these general possibilities there is one observed case of an interacting EUV wave with a bundle of adjacent coronal loops (ACLs; like case (d), where the ACL oscillation could be excited by the vortex shedding (Zhang et al 2022).…”

“…Kink oscillations are mostly detected as horizontal oscillations, while vertical oscillations are only rarely observed (Kumar et al 2022). Zhang et al (2022) performed a detailed analysis of the eruptive flare and detected the transverse vertical oscillations during the expansion of coronal loops. An example of kink and vertical oscillations of flux ropes with smallamplitude decayless oscillations were shown by Kim et al (2014).…”

Heating of Quiescent Coronal Loops Caused by Nearby Eruptions Observed with the Solar Dynamics Observatory and the Solar Upper Transition Region Imager

“…Successful flux rope eruptions push the overlying loops outward, forming bright compression fronts, which become the bright fronts of coronal mass ejections (CMEs) in coronagraphs (Li et al 2012;Yang et al 2012;Song et al 2019Song et al , 2022. They also drive the nearby coronal loops, resulting in the kinetics, such as the expansion, contraction, and oscillation, of coronal loops (e.g., Schrijver et al 2002;Mrozek 2011;Zheng et al 2013;Zhang et al 2015Zhang et al , 2022. Recently, by using images from the AIA and the New Vacuum Solar Telescope (NVST; Liu et al 2014), Li et al (2021b) reported that magnetic reconnection between loops is largely enhanced by a nearby filament eruption.…”

Transverse Vertical Oscillations During the Contraction and Expansion of Coronal Loops

“…They conjectured that a coronal wave is generated during the eruption, pushing the loops downward followed by a recovery to their initial positions. Zhang et al (2022b) studied the eruption of an EUV hot channel (flux rope) on 2022 January 20, which produced an M5.5 class flare, a fast CME, and an EUV wave. During its propagation, the EUV wave encounters and compresses low-lying adjacent coronal loops (ACLs), resulting in rapid contraction, expansion, and vertical oscillation of ACLs.…”