Empirical Modeling of CME Evolution Constrained to ACE/SWICS Charge State Distributions

Abstract

It is generally accepted that coronal mass ejections (CMEs) undergo rapid heating as they are released from the Sun. However, to date, the heating mechanism remains an open question. To gain insight into the plasma heating, we derive the density, temperature, and velocity evolution of the 2005 January 9 interplanetary CME event from launch to ion freeze-in distance by examining ion distributions collected within the ejecta near the Earth. We use the Michigan Ionization Code to simulate the ion evolution and determine thermodynamic properties through an extensive iterative search that finds agreement between simulated and observed ion populations. The final results show that the ion distributions can be effectively reconstructed using a combination of ions generated within four distinct plasma structures traveling together. Three of the modeled plasma components derived originate from the prominence and the prominence-corona transition region (PCTR) structures, while a fourth plasma shares features common to the ambient corona. The absolute abundances computed for each plasma reveal that the prominence material contains photospheric composition, while the remaining PCTR and warmer plasma have coronal abundances. Furthermore, we computed an energy release rate for each plasma structure that includes the kinetic, potential, and thermal energy rates, along with the radiative cooling, thermal conduction, and adiabatic cooling rates. We found the prominence material’s energy release rate to be consistently larger compared to the other components. In future work, the energy results will be used to investigate the feasibility of a proposed heating mechanism in an effort to gain a more comprehensive understanding of the eruption process.