Global Multi-ion Solar Wind Model. I. Ion Temperatures

Abstract

Over the past several decades, observations have shown that minor ions have a higher temperature and flow faster than protons in the solar wind. Theories based on turbulence have been developed that can explain many of these observed phenomena. We present our first step in developing a global multi-ion solar wind model with turbulence by including ion temperatures but not yet including differential streaming. The extent of this model is from the lower transition region (50,000 K temperature) to the corona and inner heliosphere. It uses low-frequency, reflection-driven incompressible turbulence to address coronal heating and solar wind acceleration. The energy partitioning of the turbulence dissipation to the electrons and various ions is based on stochastic heating and linear Landau and transit-time damping. In order to test the validity of our approach we have carried out a three-dimensional simulation of the solar corona and the solar wind using an idealized dipole magnetic field configuration, calculated the Oxygen temperature across the entire domain, and compared it to measurements obtained from the UltraViolet Coronagraph Spectrometer (UVCS) on the Solar and Heliospheric Observatory (SOHO) satellite and with the Solar Wind Ion Composition Spectrometer (SWICS) on board Advanced Composition Explorer (ACE). The comparison shows that even with the simplified magnetic field configuration the multi-ion model predictions reproduce the heavy-ion preferential heating phenomena in both remote-sensing and in-situ observations.