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Session: Heliophysics and the Solar System

Name: Dr. Eugene Zhuleku (University of Ioannina)
Coauthors: Archontis Vasilis (University of Ioannina)
Type: Oral
Title: 3D MHD magnetic flux emergence simulations of toroidal flux tubes in the Sun
Abstract:

Active regions on the Sun are produced by magnetic flux tubes emerging from the solar interior to the surface. However, previous models based on cylindrical tubes led to sunspots drifting apart for large distances, contradicting observations of sunspots with fixed distance over time. To address this discrepancy, we present results from 3D MHD simulations investigating the emergence of toroidal flux tubes with feet anchored at the base of the numerical box. This approach ensures that the emerging spots will drift apart up to a certain point, depending on the major radius of the initial toroidal tube. Using the Lare3D code, we numerically solve the 3D time-dependent compressible, resistive MHD equations in cartesian coordinates. Our simulations span from the convection zone to the corona, with a plane parallel stratification of the solar interior and atmosphere. We initiate the simulations with a toroidal magnetic flux tube at the bottom of the convection zone and let it rise buoyantly to the surface. We consider cases with and without the inclusion of a pre-existing ambient magnetic field. Our preliminary results indicate that the initial twist and size of the torus significantly impact the dynamics of the flux emergence and eruption of the emerging flux ropes. Specifically, we find that altering the size of the torus or the magnetic twist can lead to a formation and eruption of flux ropes or no eruptions at all. Furthermore, the inclusion of a pre-existing magnetic field can result in the formation of a blowout jet in some cases, while in others only a standard jet is produced. We additionally test the effect of the initial magnetic filed strength on the flux rope formation and eruption. This study presents a novel parameter investigation to identify the underlying physical parameters that govern the formation and eruption of magnetic flux ropes. Our findings have important implications for understanding the processes that drive magnetic flux emergence and eruption in the Sun. They may also provide insights useful for studying large scale eruptions that can impact space weather. Further experimentation of toroidal flux tube emergence in MHD simulations can shed light on the complex interplay between magnetic fields and plasma flows in the solar atmosphere.