The generation of outflows from the Sun known as solar winds iscoupled with the heating of the solar corona, and both processes areoperated in magnetic structures formed on the Sun. To study themagnetic configuration responsible for these processes, we usethree-dimensional magnetohydrodynamic simulations to reproducemagnetic structures via flux emergence and investigate theirconfigurations. We focus on two key quantities characterizing amagnetic configuration: the force-free parameter α and the fluxexpansion rate fex, the former of which represents how much a magneticfield is twisted while the latter represents how sharply a magneticfield expands. We derive distributions of these quantities in anemerging flux region. Our result shows that an emerging flux regionconsists of outer part where a magnetic loop takes a large fluxexpansion rate but a small value of α at their photosphericfootpoints, and inner part occupied by those loops where a strongelectric current flows. We also investigate the expansion profile of amagnetic loop composing an emerging flux region. The profile is givenby an exponential expansion type near the solar surface while it isgiven by a quadratic expansion type in an outer atmosphere. Thesedetailed magnetic configurations obtained by this study contribute todeveloping a realistic model for the coronal heating and solar windgeneration.
Authors: Hwanhee Lee, Tetsuya Magara
Publication Status: accepted
Last Modified: 2014-01-06 09:18