(Kiepenheuer-Institut für Sonnenphysik, Schöneckstrasse 6, 79104 Freiburg, Germany)
What is heating the quiet-Sun chromosphere?
It is widely believed that the heating of the chromosphere in
quiet-Sun internetwork regions is provided by dissipation of
acoustic waves that are excited by the convective motions close to
the top of the convection zone and in the photospheric overshoot
layer. This view lately became challenged by observations
suggesting that the acoustic energy flux into the chromosphere is
too low, by a factor of at least ten. Based on a comparison of TRACE
data with synthetic image sequences for a three-dimensional
simulation extending from the top layers of the convection zone to
the middle chromosphere, we come to the contradicting conclusion
that the acoustic flux in the model provides sufficient energy for
heating the solar chromosphere of internetwork regions. The role of
a weak magnetic field and associated electric current sheets is also
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