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

TL;DR

This paper reports the first EUV observations of Kelvin-Helmholtz instability in the solar corona, demonstrating vortex formation along CME interfaces and analyzing their dynamics and implications for energy transfer.

Contribution

It provides the first direct EUV observation of Kelvin-Helmholtz instability in the corona, supported by linear analysis and MHD modeling.

Findings

Vortex features observed along CME interface

Features consistent with Kelvin-Helmholtz instability

Instability driven by velocity shear between erupting and closed magnetic fields

Abstract

We present observations of the formation, propagation and decay of vortex- shaped features in coronal images from the Solar Dynamics Observatory (SDO) associated with an eruption starting at about 2:30UT on Apr 8, 2010. The series of vortices formed along the interface between an erupting (dimming) region and the surrounding corona. They ranged in size from several to ten arcseconds, and traveled along the interface at 6-14 km/s. The features were clearly visible in six out of the seven different EUV wavebands of the Atmospheric Imaging Assembly (AIA). Based on the structure, formation, propagation and decay of these features, we identified these features as the first observations of the Kelvin-Helmholtz (KH) instability in the corona in EUV. The interpretation is supported by linear analysis and by MHD model of KH instability. We conclude that the instability is driven by the velocity shear between the erupting and closed magnetic field of the Coronal Mass Ejection (CME). The shear flow driven instability can play an important role in energy transfer processes in coronal plasma.