Ion Charge States in the Solar Wind and Coronal Mass Ejections: MHD Simulations
Abstract
In situ measurements of ion fractional charge states at 1 AU and elsewhere can provide important information about electron temperatures back in the corona, since, once "frozen in," the charge states remain essentially unaltered as they travel through the solar wind. For example, high-ionization states suggest that the plasma originated from hotter regions on the solar corona. However, connecting these in situ measurements with remote spectroscopic observations has proven difficult. Using a global MHD model of the solar corona and heliosphere, which includes the self-consistent calculation of minor ion charge states, we compute the fractional charge state profiles of several ions in both the steady state solar wind and within coronal mass ejections. Our approach is based on non-equilibrium ionization calculations, which are more accurate than the standard ionization equilibrium way of computing charge states. We follow the evolution of these profiles, together with the magnetofluid parameters as the plasma propagates from the low corona to 1 AU. We discuss the results of both steady-state solutions as well as idealized CME simulations, compare them with in situ measurements, and relate them to theories for the origin of both the slow solar wind and CMEs.
- Publication:
-
Solar Heliospheric and INterplanetary Environment (SHINE 2017)
- Pub Date:
- July 2017
- Bibcode:
- 2017shin.confE..18L