Deformation and deceleration of coronal wave

¹ National Astronomical Observatories/Yunnan Astronomical Observatory, Chinese Academy of Sciences, Kunming, 650011 Yunnan, PR China
e-mail: zkxue@ynao.ac.cn
² Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, 100012 Beijing, PR China
³ University of Chinese Academy of Sciences, 100049 Beijing, PR China
⁴ Yunnan Normal University, 650092 Kunming Yunnan, PR China

Received: 14 November 2012
Accepted: 21 June 2013

Abstract

Aims. We studied the kinematics and morphology of two coronal waves to better understand the nature and origin of coronal waves.

Methods. Using multi-wavelength observations of the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) and the Extreme Ultraviolet Imager (EUVI) on board the twin spacecraft Solar-TErrestrial RElations Observatory (STEREO), we present morphological and dynamic characteristics of consecutive coronal waves on 2011 March 24. We also show the coronal magnetic field based on the potential field source surface model.

Results. This event contains several interesting aspects. The first coronal wave initially appeared after a surge-like eruption. Its front was changed and deformed significantly from a convex shape to a line-shaped appearance, and then to a concave configuration during its propagation to the northwest. The initial speeds ranged from 947 km s^-1 to 560 km s^-1. The first wave decelerated significantly after it passed through a filament channel. After the deceleration, the final propagation speeds of the wave were from 430 km s^-1 to 312 km s^-1. The second wave was found to appear after the first wave in the northwest side of the filament channel. Its wave front was more diffused and the speed was around 250 km s^-1, much slower than that of the first wave.

Conclusions. The deformation of the first coronal wave was caused by the different speeds along different paths. The sudden deceleration implies that the refraction of the first wave took place at the boundary of the filament channel. The event provides evidence that the first coronal wave may be a coronal MHD shock wave, and the second wave may be the apparent propagation of the brightenings caused by successive stretching of the magnetic field lines.