HeliSol

The HeliSol project is a « young-scientist » project in fundamental research on Heliophysics, more specifically on the Sun-Earth relationships. Its goal is to improve our previsions of the impact of solar activity on the magnetic environment of the Earth. HeliSol targets the development of innovative tools to study and understand the trigger of solar energetic events. It will focus on studying a little-exploited quantity in Solar Physics yet: magnetic helicity. Magnetic helicity is one of the few conserved quantities in Magnetohydrodynamics (MHD), the physical paradigm in which are commonly studied solar active regions. Preliminary theoretical, numerical and observational results seem to indicate that magnetic helicity likely plays a key role in solar activity. However, measurements of this quantity have so far been limited in reason of its inherent complexity. Building up on the development of new robust method of estimation of magnetic helicity, the HeliSol project will carry a thorough study of this quantity in the solar atmosphere, both from observations and thanks to state-of-the-art 3D MHD numerical simulations. From an observational point of view, HeliSol will exploit maps of the solar magnetic field provided by present space missions (e.g. Solar Dynamics Obsevatory, Hinode) in order to determine the flux of magnetic helicity through the solar surface. In parallel, 3D reconstruction methods of the atmospheric coronal field will be used to measure the volume helicity in active regions. These two types of measurements will allow the characterization of the active solar centers in term of magnetic helicity in link with their eruptivity. In addition, HeliSol will generate advanced numerical studies, relying on simulations codes working at French national high-performance computing centers (e.g. CINES). HeliSol will study the accumulation of magnetic helicity in simulations of the formation of solar active regions. These numerical studies will be compared to the observational results. Finally, the dynamics of magnetic helicity during solar eruptions will be analyzed. HeliSol will endeavor to identify in these numerical simulations the dynamics of magnetic helicity and the existence of clear criteria linking helicity with the trigger of eruptive phenomena. HeliSol will lead to the theoretical development and to the practical application of new and original methods to measure magnetic helicity in the solar atmosphere. It will generate observational and numerical studies allowing an improved understanding of the role of magnetic helicity in solar activity. HeliSol targets the derivation of proxy enabling determinist prediction of the trigger of solar eruptions. It shall induce substantial improvements in the capacity to forecast solar activity by space weather prediction centers, which current methods remains based on a heuristic approach. Beyond these applications to space weather, HeliSol is a fundamental research project which will enable a better understanding of the physical dynamics of the plasmas which are composing 99% of the visible matter of our Universe.