4D Modeling of CME expansion and EUV dimming observed with STEREO/EUVI

TL;DR

This study presents a novel 4D self-consistent model of CME expansion and EUV dimming, fitting observational data from STEREO/EUVI to understand CME kinematics and source region properties.

Contribution

The paper introduces the first quantitative 4D model of CME expansion and EUV dimming that accounts for density variations and fits observational data.

Findings

Model successfully reproduces observed CME expansion and EUV dimming.

CME expansion characterized by constant acceleration due to magnetic forces.

Detected asymmetries and density inhomogeneities in EUV observations.

Abstract

This is the first attempt to model the kinematics of a CME launch and the resulting EUV dimming quantitatively with a self-consistent model. Our 4D-model assumes self-similar expansion of a spherical CME geometry that consists of a CME front with density compression and a cavity with density rarefaction, satisfying mass conservation of the total CME and swept-up corona. The model contains 14 free parameters and is fitted to the 2008 March 25 CME event observed with STEREO/A and B. Our model is able to reproduce the observed CME expansion and related EUV dimming during the initial phase from 18:30 UT to 19:00 UT. The CME kinematics can be characterized by a constant acceleration (i.e., a constant magnetic driving force). While the observations of EUVI/A are consistent with a spherical bubble geometry, we detect significant asymmetries and density inhomogeneities with EUVI/B. This new forward-modeling method demonstrates how the observed EUV dimming can be used to model physical parameters of the CME source region, the CME geometry, and CME kinematics.