[mesa-users] Density inversions

[David Arnett]

If we do a 3D simulation (e.g., Stein and Nordlund) of these regions, we
see a tendency for two states at the same radius but different positions in
angle on the sphere. Upward moving plumes are slow, wide,  and hot, while
downward plumes are faster, narrow, and colder. Dynamics (and ram pressure)
are needed for a self-consistent interpretation. At increasingly higher
luminosity, the rising plumes are almost "radiation bubbles", which release
their photons, contract to higher density, and become falling plumes. This
is "high porosity". I think that the density inversions are simply the
response of a 1D code to this multi-D geometry.
The outer layers become dense (they try to be a downward plume) while the
underlying layers become less dense (they try to be an upward plume).

-- 
David Arnett
Regents Professor
Steward Observatory
University of Arizona

Facts are stubborn, but statistics are more pliable.  Mark Twain
Facts do not cease to exist because they are ignored.  Aldous Huxley
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