SDO/AIA Observation of Kelvin-Helmholtz Instability in the Solar Corona associated with CME

We present observations of the formation, propagation and decay of vortex-shaped features in coronal images from the Solar Dynamics Observatory (SDO) associated with Coronal Mass Ejection (CME) at about 2:34UT on Apr 8, 2010. The series of vortices are seen at 3:20UT to 3:37UT formed along the interface between erupting (dimming) region and the surrounding corona and ranged in size from several to ten arcseconds, traveling along the interface at approximately 5 km/sec. The features are clearly visible in five out of the six different EUV wavebands of the Atmospheric Imaging Assembly (AIA). Based on the structure, formation, propagation and decay of these features, we conclude that these are the first observations of the Kelvin-Helmholtz (KH) instability in the corona. The KH instability is likely driven by the velocity shear between the erupting and closed magnetic field regions. We compare the dynamics and structure of SDO/AIA observation to an MHD model of KH instability in the nonlinear stage in magnetized plasma, and find good agreement.