EUV Waves Driven by the Sudden Expansion of Transequatorial Loops Caused by Coronal Jets

Abstract

We present two events to study the driving mechanism of extreme-ultraviolet (EUV) waves that are not associated with coronal mass ejections (CMEs), by using high resolution observations taken by the Atmospheric Imaging Assembly (AIA) on board Solar Dynamics Observatory. Observational results indicate that the observed EUV waves were accompanied by flares and coronal jets, but without CMEs that were regarded as the driver of most EUV waves in previous studies. In the first case, it is observed that a coronal jet ejected along a transequatorial loop system at a plane-of-the-sky (POS) speed of 335 ± 22 km s −1 , in the meantime, an arc-shaped EUV wave appeared on the eastern side of the loop system. In addition, the EUV wave further interacted with another interconnecting loop system and launched a fast propagating (QFP) magnetosonic wave along the loop system, which had a period of 200 s and a speed of 388 ± 65 km s −1 , respectively. In the second case, we also observed a coronal jet ejected at a POS speed of 282 ± 44 km s −1 along a transequatorial loop system and the generation of bright EUV wave on the eastern side of the loop system. Based on the observational results, we propose that the observed EUV waves on the eastern side of the transequatorial loop systems are fast-mode magnetosonic waves, and they were driven by the sudden lateral expansion of the transequatorial loop systems due to the direct impingement of the associated coronal jets, while the QFP wave in the fist case formed due to the dispersive evolution of the disturbance caused by the interaction between the EUV wave and the interconnecting coronal loops. It is noted that EUV waves driven by sudden loop expansions have shorter lifetimes than those driven by CMEs.

Coronal EUV, QFP, and kink waves simultaneously launched during the course of jet–loop interaction

“…This scenario has been confirmed by many observations and theoretical studies of the separation process between CMEs and waves (e.g., Long et al 2008;Gopalswamy et al 2009;Olmedo et al 2012;Yang et al 2013;Shen et al 2013bShen et al , 2017b. In addition, EUV waves can also be driven by sudden loop expansions caused by external disturbances (Shen et al 2018d) and coronal jets (Shen et al 2018a). For more details of EUV waves, one can refer to Liu & Ofman (2014) and Warmuth (2015).…”

“…For the EUV wave, its lifetime is much shorter than typical hour-long lifetime of normal EUV waves driven by CMEs (see, Liu & Ofman 2014, and reference therein). However, it is similar to the EUV waves driven by sudden loop expansions caused by the impingement of external eruptions such as jets (Shen et al 2018d), or the ex-pansion of the newly formed reconnected loops resembling of the slingshot mechanism in the eruption of coronal jets (e.g., Su et al 2015). Since no CME was associated with the present event, and considering the temporal and spatial relationship between the EUV wave and the jet, we therefore propose that the observed EUV wave was possibly excited by the sudden expansion of the interconnecting loop system caused by the impingement of the coronal jet, supporting the recent observational results presented in Shen et al (2018d).…”

Observation and modelling of solar jets

“…Although many previous studies have shown that large-scale EUV waves are driven by CMEs [226][227][228][229][230], recent observations suggest that they can also be launched by solar jets directly or indirectly. Shen et al [231] reported that large-scale non-CME-associated EUV waves were excited by the sudden lateral expansion of transequatorial loops owing to the impingement of solar jets, in which the generation of the waves was caused by the sudden increase of gas and magnetic pressures around the expansion section of the loop. In a subsequent study, they further reported the generation of recurrent fast-mode EUV waves ahead of homologous jets along a large-scale transequatorial loop system (figure 8); they explained that the excitation mechanism of these waves resembles the generation mechanism of a piston shock in a tube [94].…”

Research progress on coronal extreme ultraviolet waves

“…EUV波的 快慢分量均可导致静止波前的形成, 其中慢成分导致 的静止波前更适合非波模型的解释 [107] , 而快波成分导 致的静止波前可能是由部分快磁声波转化为慢磁声波 并被束缚在磁力线中所导致 [108,109] . 另外, EUV波与磁 环作用时还可转化为QFP波 [95] . 有时, 可在EUV波后方 观测到区别于爆发源区的次级日冕暗化现象 [10] , 其形 成原因可能是流绳爆发导致的等离子体流失, 也可能 是EUV波经过后介质的回复导致的等离子体变稀 疏 [76] .…”

“…大多数QFP波的激发可能与引发耀斑的磁重联 过程中的非线性物理过程密切相关 [21,23,25,137,139] , 例如 电流片中等离子体团的分裂、合并和喷射 [140,141] 以及 振荡重联等 [142] . 同时, 部分观测结果显示, 太阳爆发扰 动在非均匀介质中通过色散式演化 [24,94,95] , 而光球压 力模向上泄漏到日冕 [21,22]…”