STEREO quadrature observations of the 3D structure and driver of a global coronal wave

TL;DR

This paper reports the first quadra-ture observations of a global coronal wave, revealing its 3D structure, initiation mechanism, and propagation characteristics, which are linked to CME lateral expansion and fast magnetosonic speed.

Contribution

It provides unprecedented 3D observations of a coronal wave from STEREO satellites, clarifying its initiation and propagation mechanisms.

Findings

Wave propagates globally with a velocity of 263+/-16 km/s.

Wave height is estimated at 80-100 Mm.

Wave initiated by CME lateral expansion.

Abstract

We present the first observations of a global coronal wave ("EIT wave") from the two Solar Terrestrial Relations Observatory (STEREO) satellites in quadra- ture. The wave's initiation site was at the disk center in STEREO-B and precisely on the limb in STEREO-A. These unprecedented observations from the STEREO Extreme Ultraviolet Imaging (EUVI) instruments enable us to gain insight into the wave's kinematics, initiation and 3D structure. The wave propagates globally over the whole solar hemisphere visible to STEREO-B with a constant velocity of 263+/-16 km/s. From the two STEREO observations we derive a height of the wave in the range of 80-100 Mm. Comparison of the wave kinematics with the early phase of the erupting CME structure indicates that the wave is initiated by the CME lateral expansion, and then propagates freely with a velocity close to the fast magnetosonic speed in the quiet solar corona.