SHINE: Constraining Solar Wind and Coronal Mass Ejection (CME) Models Using in situ Ionic Composition Observations

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

The PI proposes to utilize and model in situ solar wind charge states measured by the Advanced Composition Explorer (ACE) and Ulysses spacecraft since 1998. He plans to solve critical science questions regarding the source and acceleration of the slow and fast solar wind, the boundaries separating them, and the initiation mechanism of Interplanetary Coronal Mass Ejections (ICMEs). The proposed work will require collaboration between solar and heliospheric physicists and lead the SHINE community to an improved understanding of the corona and heliospheric systems as a whole. This dedicated effort seeks to reconcile theories with observations, enabling the determination of compositional and thermal constraints for CME and solar wind models. Solar wind ionic composition is a unique and important measure of the thermal environment of its coronal source region, as well as the source regions of plasma associated with ICMEs. Charge states in the solar wind reflect the electron temperatures in the inner corona, and the thermal history of the solar wind can be used to determine expansion properties and heat deposition in the low corona. This effort builds upon previous work that has shown that ionic charge states of heliospheric plasmas are crucial in identifying ICMEs and analyzing the sources of energetic particles accelerated in the heliosphere. The proposers will develop a freeze-in code to model the expansion and ionization of solar wind ions under a variety of coronal conditions. They will apply physics models that will enable the calculation and comparison of the modeled coronal electron temperatures with the observed ionization states from in situ data. The PI will subsequently construct radial temperature profiles by considering ions that freeze-in at different heliocentric radii. The results of the proposed work will provide the most comprehensive analysis of the thermal history of the solar wind close to the Sun, based on a complete set of measurements of in situ ionization states.