Numerical Investigation of a Coronal Mass Ejection from an Anemone Active Region: Reconnection and Deflection of the 2005 August 22 Eruption

TL;DR

This study uses 3D magnetohydrodynamic simulations to analyze the evolution, reconnection, and deflection of a 2005 CME originating from an anemone active region, comparing results with observations.

Contribution

It provides a detailed numerical analysis of CME reconnection, deflection, and magnetic topology changes from an anemone active region, validated by synthetic and real EUV images.

Findings

CME experienced about 3°/Rsun eastward deflection due to Lorentz forces.

Reconnection altered the magnetic field structure, creating open and closed field lines.

No significant rotation of the CME was observed during propagation.

Abstract

We present a numerical investigation of the coronal evolution of a coronal mass ejection (CME) on 2005 August 22 using a 3-D thermodynamics magnetohydrodynamic model, the SWMF. The source region of the eruption was anemone active region (AR) 10798, which emerged inside a coronal hole. We validate our modeled corona by producing synthetic extreme ultraviolet (EUV) images, which we compare to EIT images. We initiate the CME with an out-of-equilibrium flux rope with an orientation and chirality chosen in agreement with observations of a H-alpha filament. During the eruption, one footpoint of the flux rope reconnects with streamer magnetic field lines and with open field lines from the adjacent coronal hole. It yields an eruption which has a mix of closed and open twisted field lines due to interchange reconnection and only one footpoint line-tied to the source region. Even with the large-scale reconnection, we find no evidence of strong rotation of the CME as it propagates. We study the CME deflection and find that the effect of the Lorentz force is a deflection of the CME by about 3 deg/Rsun towards the East during the first 30 minutes of the propagation. We also produce coronagraphic and EUV images of the CME, which we compare with real images, identifying a dimming region associated with the reconnection process. We discuss the implication of our results for the arrival at Earth of CMEs originating from the limb and for models to explain the presence of open field lines in magnetic clouds.