[P-EM09] Space Weather and Space Climate

[PEM09-06] How do active regions of the Sun inject magnetic helicity and cause flare eruptions?

★Invited Papers

*Shin Toriumi¹ (1.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency)

Keywords:Solar flares, Coronal mass ejection, Magnetic helicity, Numerical simulations

Solar flares and coronal mass ejections occur as a result of magnetic helicity injection in the corona via the magnetic flux emergence from the deep convection zone. However, because optical observation of the solar interior is impossible, it is not well understood how the emerging flux creates flare-productive active regions and how magnetic helicity is injected into the corona. To address this issue, we simulate the emergence of a twist-free magnetic flux tube using the radiative magnetohydrodynamic code R2D2, which self-consistently solves the realistic thermal convection in a deep domain. The results show that the untwisted flux tube can reach the solar surface with the support of convective upflow and creates an active region, as opposed to the previous prediction that an untwisted flux tube fails to emerge owing to the strong counteracting aerodynamic drag. The helicity injection measured in the photosphere is finite (non-zero) and amounts to about 50% of that for the twisted cases. Detailed analysis reveals that the helicity injection occurs because local eddies in the convection rotate the sunspots, which indicates that the turbulent convection is a hidden significant supplier of magnetic helicity and may contribute to flare eruptions. In the presentation, we will review key observations regarding the formation of flare-productive active regions and present state-of-the-art results from numerical modeling.