jeudi 7 juin 2018, par Spiro K. Antiochos (NASA/GSFC, USA)
Lundi 25 juin 2018 à 11h00 , Lieu : Salle de rĂ©union du bâtiment 16
It is now widely believed that solar eruptions such as CMEs, eruptive flares, and coronal hole jets are all due to the explosive release of magnetic free energy stored in the corona ; specifically, in the highly stressed magnetic field that supports filaments and prominences. An important observational finding in recent years is that the mechanisms underlying these eruptions may be invariant over many decades in energy release. We have proposed that the formation of the filament field and, consequently, the free energy buildup, is due to an inverse cascade of magnetic helicity injected into the corona by motions and flux emergence at the photosphere. We present our latest 3D MHD numerical simulations of the self-consistent energy buildup by helicity condensation and eventual explosive energy release. The calculations are in a realistic spherical domain that extends outward to 30 solar radii. We conclude from these simulations that the onset for the eruption, the trigger mechanism, is magnetic reconnection in the coronal field overlying the filament. Our results demonstrate that solar eruptions are an amazing example on cosmic scales of self-organization leading to catastrophic dynamics.
