The Kelvin-Helmholtz Instability at CME-Boundaries in the Solar Corona: Observations and 2.5D MHD Simulations

TL;DR

This study combines solar observations and 2.5D MHD simulations to analyze Kelvin-Helmholtz instability at CME boundaries, revealing how magnetic fields influence asymmetry in vortex formation.

Contribution

It provides the first detailed comparison between observed vortex structures and numerical simulations of Kelvin-Helmholtz instability at CME boundaries.

Findings

Observed vortex wavelength ~14.4 Mm and speed ~310 km/s.

Simulations show qualitative and quantitative agreement with observations.

Magnetic field component parallel to boundary stabilizes vortex development.

Abstract

The Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory observed a coronal mass ejection with an embedded filament on 2011 February 24, reavealing quasi-periodic vortex-like structures at the northern side of the filament boundary with a wavelength of approximately 14.4 Mm and a propagation speed of about 310 +- 20 km/s. These structures could result from the Kelvin-Helmholtz instability occurring on the boundary. We perform 2.5D numerical simulations of the Kelvin-Helmholtz instability and compare the simulated characteristic properties of the instability with the observations, where we obtain qualitative as well as quantitative accordance. We study the absence of Kelvin-Helmholtz vortex-like structures on the southern side of the filament boundary and find that a magnetic field component parallel to the boundary with a strength of about 20% of the total magnetic field has stabilizing effects resulting in an asymmetric development of the instability.