Magnetic Flux Tube Dynamics in the Deep Solar Interior

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My doctoral work focused on the magnetic field transport processes in the deep interior of the Sun and their eventual observational signatures at the solar surface. This work emerged from the desire to understand flux tube dynamics under more realistic initial conditions. To this effect, we studied the rise of non-isolated toroidal flux tubes through a volume-filling large-scale magnetic field, with and without the presence of convection. We find that positive and negative twisted flux tubes show starkly different dynamics. In particular, for a given large-scale magnetic field (B_s), flux tubes of one sign of the twist are more likely to rise than the other. We created a mathematical model based on the forces acting on the flux tube that can explain and even predict the observed asymmetric rise dynamics for a given flux tube twist and background field orientation. This reveals a filtering region in the parameter space that we refer to as the Selective Rise Regime (SRR). To better understand the statistical relevance of the SRR, we carried out Monte Carlo (MC) simulations of multiple flux tubes rising through the background field. This study further shows that the SRR, along with the MC simulations, plausibly explains the broad range of solar helicity observations that are collectively known as the Solar Hemispheric Helicity rules (SHHR). In the presence of convection, the dynamics get more realistic and complex. Despite the presence of much more complicated dynamics, we still find the same preferential rise of flux tubes of a particular twist, thus establishing the robustness of the SRR mechanism. To conclude, we propose a new mechanism that can explain in detail the various salient features of solar observations of magnetic and current helicity.

I am currently working with Ben Brown and the Dedalus group as a postdoc at Laboratory for Atmospheric and Space Physics (LASP), CU Boulder.

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Congrats Bhishek!