[Mesa-users] Adding variables to profile from model file

[GM Mirouh]

Dear all,

I have computed and saved MESA models for a range of parameters, and in 
making progress I realised that I did not save some variables that I 
need now. I am looking for a trick to add those new columns to my 
profiles and history files, retrieving them somehow from the model file 
I've saved during my original calculation.

To avoid recomputing all my stellar evolution tracks, I have tried to 
restart from a model files and take one small timestep with more 
complete history_columns and profile_columns files. I was expecting this 
to yield a new model, very close to the previous one, with new columns 
in the profile file for that timestep. However, the structures I get are 
different, especially in the core, and playing with mixing or timestep 
parameters does not seem to help.


Here are more details:
- I am using MESA 12115

- I have attached a plot for a M=2.24 Msun near-TAMS profile, where the 
convective core is small. After I do my small timestep, the structure 
now has a fully mixed core in the which the gradient difference <0 (so, 
it's radiative now, I guess?). The surface also changes quite a bit...
I can provide model, inlist or profile files for comparison if need be.

- I have tried taking timesteps of 1 and 1e-4 years, with and without 
convective premixing, changing the mixing length or using 
dxdt_nuc_factor = 0 : none of these made a visible difference, the core 
was still strangely mixed.


I feel I might be missing a parameter here, that could "freeze" mixing, 
but could not find anything like this. Maybe someone has already worked 
out such a trick or a different approach to the same issue?

As always, thank you very much for any help you can provide.
Best.
-- 
Gio.

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