[mesa-users] stellar-structural noise

[Alfred Gautschy]

Bill,

thanks for your input!

> Just to follow up on Aaron's suggestion to check the EOS transitions,  the 1st to try is the temperature boundary between HELM and OPAL.  You can move it with these controls in &star_job
> 
>       ! transition temperature zone for OPAL to HELM at high T
>       set_HELM_OPAL_lgTs = .false.
>       logT_all_HELM = 7.7d0 ! HELM for lgT >= this
>       logT_all_OPAL = 7.6d0 ! OPAL/SCVH for lgT <= this
> 
In the background my computer is working on your EoS transition
suggestion. I will comment on the tests as soon I got some overview.

> What is the exact code you use to get U?  Perhaps something might show up there. 
> 
It is a *really* simple formula, and also performed well over the years:

   U = 4*pii*rsol3*10**(3*lgr+lgrho)/mss

rsol3: (solar radius)**3 since r is given in solar units
lgrho: log10(rho) of rho in cgs
mss  : mass in cgs

I account for the staggered mesh and interpolate rho to the interfaces; 
however, whatever I do - right or wrong, so to say - the wiggles are
unimpressed!

Just to make sure I did not miss a problem already in the dark past, I
plotted also parts of the terms; the plots showed that the whole
business is indeed well behaved ...except for some very slight changes
in slopes in lgr and lgrho as a function of depth in the star (just the
places I see the wiggles in the final quantity U).
 
Regards, Alfred