[Mesa-users] convergence problems in specific mass range

[Thomas Steindl]

Hello everyone,

I am running the same inlist for masses between 0.5 and 6 solar masses  
with steps of 0.05 solar masses. For some reason, the evolution of the  
0.55 solar mass model stops after roughly 1800 steps. All other masses  
work. If I change the mass to 0.54 solar masses, it works (same for  
0.56). Therefore, there is something weird happening in the mass range  
around 0.55. I have been looking at the temperature, pressure, opacity  
and density profiles, yet I cannot find unexpected behavior.

To clarify what happens: I am using MESA version r11532. At some point  
MESA starts doing retrys and backups until the timestep is to small.  
Taking a smaller limit for min_timestep_limit does not work - it will  
still stop. I have been checking the output of the newton solver - it  
takes up to 25 iterations at the end until giving up either because of  
average, max resid or tiny corrections. Additionally, using things  
like soften_grad_T do not improve the convergence substantially, the  
evolution just stops a few steps later.

I am attaching the inlist. I would appreciate any help for resolving  
this problem. Thank you very much in advance.

kind regards,
Thomas
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