Tracking the 3D evolution of a halo coronal mass ejection using the revised cone model

TL;DR

This study uses a revised cone model with multi-point observations to track the 3D evolution of a halo CME, revealing its morphology, kinematics, and rapid expansion with improved accuracy over previous methods.

Contribution

The paper introduces a modified cone model with a spherical top for better 3D tracking of CMEs, validated with multi-spacecraft data, enhancing understanding of CME evolution.

Findings

The cone angle increases sharply during initial expansion.

The true CME speed is about 1.6 times higher than apparent speed.

The model effectively tracks CME morphology and kinematics.

Abstract

This paper aims to track the 3D evolution of a full halo CME on 2011 June 21. The CME results from a non-radial eruption of a filament-carrying flux rope in NOAA active region 11236. The eruption is observed in EUV wavelengths by the EUVI on board the ahead and behind STEREO spacecrafts and the AIA on board SDO. The CME is observed by the COR1 coronagraph on board STEREO and the C2 coronagraph on board SOHO/LASCO. The revised cone model is slightly modified, with the top of the cone becoming a sphere, which is internally tangent to the legs. Using the multi-point observations, the cone model is applied to derive the morphological and kinematic properties of the CME. The cone shape fits nicely with the CME observed by EUVI and COR1 on board STEREO twin spacecraft and LASCO/C2 coronagraph. The cone angle increases sharply from 54$^{\circ}$ to 130$^{\circ}$ in the initial phase, indicating a rapid expansion. A relation between the cone angle and heliocentric distance of CME leading front is derived, $\omega=130\degr-480d^{-5}$, where $d$ is in unit of $R_{\odot}$. The inclination angle decreases gradually from $\sim$51$^{\circ}$ to $\sim$18$^{\circ}$, suggesting a trend of radial propagation. The heliocentric distance increases gradually in the initial phase and quickly in the later phase up to $\sim$11\,$R_{\odot}$. The true speed of CME reaches $\sim$1140 km s$^{-1}$, which is $\sim$1.6 times higher than the apparent speed in the LASCO/C2 field of view. The revised model is promising in tracking the complete evolution of CMEs.