Determining CME Evolution Near the Sun by Modeling the Charge State Distribution of CME plasmas

Coronal Mass Ejections (CMEs) are some of the largest, most energetic events in the solar system expelling a significant amount of charged particles and magnetic field into the Heliosphere. Earth-bound plasma can trigger geomagnetic storms causing damage to satellites, disrupting communication signals and navigation systems. As a CME launches through the interplanetary medium it undergoes heating, expansion and acceleration. How the plasma is heated as it lifts out of the corona is significant to its evolution and geoeffectiveness, and yet is still not well understood. Previous work has shown that the ions in the plasma 'freeze-in' to their final charge state at distances within a few solar radii from the Sun, and stay unaltered until they reach Earth. This property makes them a good indicator of thermal conditions in the corona, where the CME plasma likely receives most of its heating. We model the evolution of the ionization states of Carbon, Oxygen, Magnesium and Iron in an Earth-directed CME to derive empirical models of the plasma heating and evolution. We focus on the event on January 9th 2005 using the ionic abundances collected with the Solar Wind Ion Composition Spectrometer (SWICS) on the Advanced Composition Explorer (ACE) spacecraft. We empirically determine the electron temperature, density and bulk velocity of plasma along its trajectory by iteratively adjusting ion abundances predicted by a plasma ionization code to match the observed charge state distributions. In future work, the models developed from this research will be used to estimate many components of the energy budget to gain insight on the heating near the Sun.