Research

Speaker: Elizabeth Wraback

High-resolution EUV spectroscopy of the corona provides the most informative diagnostic tool for the early evolution of coronal mass ejections (CMEs) since it can directly measure many physical properties of CME plasma close to the Sun, which cannot be determined from white light coronagraphs and narrow-band imagers. In-situ charge state observations can show the fingerprint of the plasma from early in its evolution. However, CMEs are inherently dynamic structures, undergoing significant change during its evolution, making it difficult to draw a connection between the remote sensing observations and the in-situ charge state measurements. Therefore, we can use tools, such as magnetohydrodynamics models, to attempt to connect these different types of observations. Hinode/EIS captured its full range of high-resolution EUV spectra of the April 9th, 2008, event, also known as the Cartwheel CME, during its initial acceleration period. Unique to this work, simulations of the Cartwheel CME with the Alfvén Wave Solar atmosphere Model (AWSoM) and the Gibson-Low flux rope model, were performed to provide insight into the plasma structure and dynamics during the early evolution of this CME. For the first time, we combined self-consistent non-equilibrium charge state calculations in the EUV spectral line synthesis for a CME simulation, to account for the plasma departures from ionization equilibrium everywhere in the CME. Overall, the model is able to reproduce the thermodynamic evolution of the CME in the low solar corona, as compared to the EIS observations. We discuss the thermodynamic evolution of CME’s plasma structure as the non-equilibrium charge states freeze-in to understand what is driving the plasmas’ evolution through the solar corona.