Given below is a set of movies of stellar models close to the main-sequence
from
`T`_{eff}=9000K (A type star with very inefficient convection)
over
`T`_{eff}=5770K (Sun with efficient, deep-reaching convection)
to
`T`_{eff}=4500K.
All have solar composition.
The temperature is color-coded. The velocity field is indicated by tracer
particles. For models with effecitive temperatures of 7250K and above the
convection zones are shallow enough to be completely included in the
computational volume. A simple closed lower boundary conditions can be employed.
At `T`_{eff}=7000K and below the convection zone extends far
downward and can penetrate the lower boundary of the computational box.
Accordingly, a sophisticated open lower boundary condition is used.

The code was mainly written by Matthias Steffen. The expert for the opacity stuff is Hans-Günter Ludwig.

A technical remark concerning the following MPEG movies: A standard frame rate
of 30 frames per second results in only a short animation with rather fast
motion. I would recommend a lower frame rate, e.g. with:

```
mpeg_play -framerate 12 -dither color -quiet -loop cxh100_04a_T.mpg &
```

Sun (`T`_{eff}=5770K, log`g`=4.44, [M/H]=0)
model L71D09:
19MB-MPEG,
1.4MB-MPEG

A star (`T`_{eff}=9000K, log`g`=4.40, [M/H]=0)
model at90g44n4:
10MB-MPEG,
2.0MB-MPEG

A star (`T`_{eff}=8500K, log`g`=4.40, [M/H]=0)
model at85g44n04:
9.0MB-MPEG,
1.4MB-MPEG

A star (`T`_{eff}=8000K, log`g`=4.40, [M/H]=0)
model at80g44n7:
14MB-MPEG,
1.8MB-MPEG

A star (`T`_{eff}=7500K, log`g`=4.40, [M/H]=0)
model at75g44n5:
29MB-MPEG,
2.0MB-MPEG

F star (`T`_{eff}=7250K, log`g`=4.44, [M/H]=0)
model at70g44n2:
28MB-MPEG,
2.7MB-MPEG

F star (`T`_{eff}=7000K, log`g`=4.44, [M/H]=0)
model gt70g44n2:
19MB-MPEG,
1.7MB-MPEG

G star: Sun (`T`_{eff}=5770K, log`g`=4.44, [M/H]=0)
model L71D09:
19MB-MPEG,
1.4MB-MPEG

K star (`T`_{eff}=4500K, log`g`=4.44, [M/H]=0)
model gt45g44n3:
18MB-MPEG,
1.5MB-MPEG

metal-poor G star: (`T`_{eff}=5770K, log`g`=4.44, [M/H]=-2)
model OT57G44N7:
24MB-MPEG

metal-poor F star: (`T`_{eff}=6300K, log`g`=4.00, [M/H]=-2)
model OT63G40N2:
26MB-MPEG

A collaboration between Sven Wedemeyer (Freiburg), Hartmut Holweger (Kiel), Matthias Steffen (Potsdam), and myself has lead to some preliminary results about the contribution of convection to chromospheric heating. Below you can find some examples. For more details visit Sven Wedemeyer's homepage.

Grey opacities (Sun, `T`_{eff}=5770K, log`g`=4.44, [M/H]=0)
model cxh100_02:
temperature fields: 2.6MB-MPEG,
temperature over height: 1.4MB-MPEG.

Grey opacities (Sun, `T`_{eff}=5770K, log`g`=4.44, [M/H]=0)
model cxh100_04:
temperature fields: 2.6MB-MPEG,
temperature over height: 1.4MB-MPEG.

Frequency-dependent opacities (Sun, `T`_{eff}=5770K, log`g`=4.44, [M/H]=0)
model cxh100_06:
temperature fields: 1.4MB-MPEG,
temperature over height: 1.1MB-MPEG.

Below, you find some preliminary results of my current efforts to set up a simulation of a red supergiant, a whole "Star in a Box". There are movies of the surface intensities of all six sides of the computational cube. The code was mainly developed during my stay in Copenhagen in the group of Åke Nordlund.

Due to numerical problems with the extremely sharp temperature jump at the surface of a "real" supergiant, I had to scale some models to shift the surface conditions into a regime which is easier to handle. This applies for the "easy" and the "intermediate" model run. The model st33gm06n03 is the first "real" thing.

You can find some additional information in Betelgeuse -- Towards Numerical Simulations of an Entire Supergiant, Bernd Freytag, 2000, (Poster presented at the ``International Scientific Meeting of the Astronomische Gesellschaft'' September 18-23, 2000, Bremen, Germany).

"Easy" model st57g44n01-06, surface intensity: 1.4MB-MPEG

"easy" model st57g44n01-06, surface intensity: 1.2MB-MPEG

"easy" model st57g44n01-06, surface intensity: 1.3MB-MPEG

"easy" model st57g44n01-06, surface intensity: 1.3MB-MPEG

"easy" model st57g44n01-06, surface intensity: 1.3MB-MPEG

"easy" model st57g44n01-06, surface intensity: 1.3MB-MPEG

"easy" model st57g44n01-06, temperature slice: 1.6MB-MPEG

"easy" model st57g44n01-06, temperature slice (different color table): 1.6MB-MPEG

"easy" model st57g44n01-06, pressure slice: 1.5MB-MPEG

"easy" model st57g44n01-06, entropy slice: 1.7MB-MPEG

"easy" model st57g44n01-06, entropy slice (different color table): 1.7MB-MPEG

"intermediate" model st47g20n05_01-02, surface intensity: 0.3MB-MPEG

"intermediate" model st47g20n05_01-02, surface intensity: 0.3MB-MPEG

"intermediate" model st47g20n05_01-02, surface intensity: 0.3MB-MPEG

"real" model st33gm06n03_00-45, surface intensity: 6.0MB-MPEG

"real" model st33gm06n03_00-45, surface intensity: 6.0MB-MPEG

"real" model st33gm06n03_00-45, surface intensity: 6.0MB-MPEG

"real" model st33gm06n03_00-45, temperature + blobs: 14.5MB-MPEG

Back to Bernd Freytag's homepage.