Quadrature observations of wave and non-wave components and their decoupling in an extreme-ultraviolet wave event

Abstract

We report quadrature observations of an extreme-ultraviolet (EUV) wave event on 2011 January 27 obtained by the Extreme Ultraviolet Imager on board the Solar Terrestrial Relations Observatory, and the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. Two components are revealed in the EUV wave event. A primary front is launched with an initial speed of ∼440kms-1. It appears that significant emission enhancement occurs in the hotter channel while deep emission reduction occurs in the cooler channel. When the primary front encounters a large coronal loop system and slows down, a secondary, much fainter, front emanates from the primary front with a relatively higher starting speed of ∼550kms-1. Afterward, the two fronts propagate independently with increasing separation. The primary front finally stops at a magnetic separatrix, while the secondary front travels farther until it fades out. In addition, upon the arrival of the secondary front, transverse oscillations of a prominence are triggered. We suggest that the two components are of different natures. The primary front belongs to a non-wave coronal mass ejection (CME) component, which can be reasonably explained with the field-line stretching model. The multi-temperature behavior may be caused by considerable heating due to nonlinear adiabatic compression on the CME frontal loop. As for the secondary front, it is most likely a linear fast-mode magnetohydrodynamic wave that propagates through a medium of the typical coronal temperature. X-ray and radio data provide us with complementary evidence in support of the above scenario. © 2012. The American Astronomical Society. All rights reserved.