Magnetic Flux Emergence in the Solar Photosphere

摘要

The most prominent magnetic structures on the surface of the Sun are bipolar active regions. These magnetic complexes are comprised of a hierarchy of magnetic structures of different sizes, the largest of which are sunspots.Observations indicate that the appearance of active regions on the solar surface result from the emergence of bundles of magnetic flux from the underlying convection zone. We study the emergence process by means of 3D radiation MHD simulations. In the simulations, an initially buoyant magnetic flux tube is introduced into the near-surface layers of the convection zone. Subject to the buoyancy force, the flux tube rises towards the photosphere. Our simulations highlight the importance of magneto-convection on the evolution of the magnetic flux tube. The external convective flow field has an important influence on the emergence morphology of the emerging magnetic field. Depending on the initial properties of the magnetic flux tube (e.g. field strength, twist, entropy etc.),flux emergence may lead to a disturbance of the local granulation pattern. The observational signatures associated with emerging magnetic flux in our simulations are in qualitative and quantitative agreement with observational studies of emerging flux regions on the Sun.