(Kiepenheuer-Institut für Sonnenphysik, Schöneckstrasse 6, 79104 Freiburg, Germany)
Dynamic Models of the Sun from the Convection Zone to the Chromosphere
The chromosphere in internetwork regions of the quiet Sun was
regarded as a static and homogeneous layer for a long time. Thanks
to advances in observations and numerical modelling, the wave nature
of these atmospheric regions received increasing attention during
the last decade. Recent three-dimensional radiation
magnetohydrodynamic simulations with CO5BOLD feature the
chromosphere of internetwork regions as a dynamic and intermittent
phenomenon. It is a direct product of interacting waves that form a
mesh-like pattern of hot shock fronts and cool post-shock regions.
The waves are excited self-consistently at the top of the convection
zone. In the middle chromosphere above an average height of 1000 km,
plasma beta gets larger than one and magnetic fields become more
important. The model chromosphere exhibits a magnetic field that is
much more homogeneous than in the layers below and evolves much
faster. That includes fast propagating (MHD) waves. Further
improvements of the simulations like time-dependent hydrogen
ionisation are currently in progress. This class of models is
capable of explaining apparently contradicting diagnostics such as
carbon monoxide and UV emission at the same time.
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