Limb Observations of Global Solar Coronal Extreme-ultraviolet Wavefronts: The Inclination, Kinematics, Coupling with the Expanding Coronal Mass Ejections, and Connection with the Coronal Mass Ejection Driven Shocks

TL;DR

This study analyzes six limb solar EUV wave events to understand their inclination, speed, coupling with CMEs, and connection with shocks, revealing their propagation characteristics and interactions with coronal structures.

Contribution

It provides new measurements of EUV wavefront inclination and speed, and explores their coupling with CMEs and shocks, using limb observations to avoid projection effects.

Findings

Wavefront inclination affects speed estimates.

Wavefront speed can be increased by nearby loop systems.

EUV wavefronts are coupled with CME drivers in some events.

Abstract

We select and investigate six global solar extreme-ultraviolet (EUV) wave events using data from the Solar Dynamics Observatory and the Solar and Heliospheric Observatory. These eruptions are all on the limb but recorded as halo coronal mass ejections (CMEs) because the CME-driven shocks have expanded laterally to the opposite side. With the limb observations avoiding the projection effect, we have measured the inclination and speed of the EUV wavefront from 1.05 to 1.25 $R_\odot$. We also investigate the coupling and connection of the EUV wavefront with the CME boundary and the CME-driven shock, respectively. The major findings in the six events are: (1) the forward inclination of the primary and coronal-hole-transmitted EUV wavefronts is estimated, respectively, and the origins of these inclinations and their effects on the estimate of actual wavefronts speed are investigated; (2) the wavefront speed can be elevated by loop systems near the coronal base, and the average speed in the low corona has no clear correlation with the lateral expansion of the CME-driven shock in the high corona; (3) the fast magnetosonic Mach number of the wavefront is larger than unity from the coronal base; (4) the EUV wavefront is coupled with the CME driver throughout the propagation in two events; (5) after the EUV wavefront vanishes, the CME-driven shock continues traveling on the opposite side and disconnects from the EUV wavefront in four events. These results and their implications are discussed, which provide insight into the properties of global EUV waves.