Cross-loop propagation of a quasi-periodic extreme-ultraviolet wave train triggered by successive stretching of magnetic field structures during a solar eruption

TL;DR

This paper reports the observation of a quasi-periodic EUV wave train during a solar eruption, revealing a two-component structure consistent with theoretical models of fast magnetoacoustic waves and slower magnetic field stretching.

Contribution

It provides observational evidence of a two-component EUV wave structure and links the wave train to successive magnetic field stretching during a solar eruption.

Findings

Detected a quasi-periodic wave train with ~120 s period.

Identified two distinct propagation speeds: ~308 km/s for the wave and ~95 km/s for the loop expansion.

Supported the two-component EUV wave model involving fast waves and magnetic stretching.

Abstract

Solar extreme-ultraviolet (EUV) waves generally refer to large-scale disturbances propagating outward from sites of solar eruptions in EUV imaging observations. Using the recent observations from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO), we report a quasi-periodic wave train propagating outward at an average speed of $\sim$308 km s$^{-1}$. At least five wavefronts can be clearly identified with the period being $\sim$120 s. These wavefronts originate from the coronal loop expansion, which propagates with an apparent speed of $\sim$95 km s$^{-1}$, about 3 times slower than the wave train. In the absence of a strong lateral expansion, these observational results might be explained by the theoretical model of Chen et al. (2002), which predicted that EUV waves may have two components: a faster component that is a fast-mode magnetoacoustic wave or shock wave and a slower apparent front formed as a result of successive stretching of closed magnetic field lines. In this scenario, the wave train and the successive loop expansion we observed likely correspond to the fast and slow components in the model, respectively.