[Mesa-users] problem with small time-steps

[Francis Timmes]

hi ebrahim,

my impression is you need to do a deeper analysis to sort out the issues with your model.
changing a parameter and simply reporting success or failure is not sufficient.

for example, plot the abundances as a function of mass, the luminosities (he, he, total) 
at the core and surface as a function of model number (or time), the mixing history of 
the models, the temperature, density, and energy generation profiles as the model evolves,
and perhaps most importantly the magnitude of your dark matter correction as a function of 
model number and/or mass coordinate. you should check that these quantities are producing 
reasonable physical results as the model evolves, and thus be able to say definitively 
what is happening with the model if the timestep stalls.

good luck!

fxt







> On Jan 26, 2022, at 8:31 AM, Ebrahim Hassani <ee.haji at gmail.com> wrote:
> 
> Dear Mesa-users
> 
> Thank you very much for all of your comments and feedback on my questions.
> 
> During the last few days, I struggled with the problem and tested all of your suggestions. Especially, I uncommented the stellar-mass-loss lines (i.e. lines No 56-62) in the "inlist_project" file (in the attached file in the first email). This time I let the star evolve until step-number ~70000. The attached files are the H-R diagram and a screenshot of my terminal. My guess is, the 2 M_Sun star is struggling in the thermally-pulsing asymptotic giant branch (TP-AGB) stage more than other stars (As Dr. Warrick mentioned in the previous email).
> 
> It is worth mentioning that, for 2 M_Sun star, when I considered dark matter effects (by considering dark matter density to be about 10^4 times the dark matter density around the sun, and in line 324 in the run_star_extras.f90 file), the star evolved until the white-dwarf phase successfully (in about 20000 steps). But when I reduced the dark-matter density to about the same amount as the dark matter density around the sun, the star did not reach the white dwarf phase after about 70000 steps.
> 
> I appreciate any of your comments and suggestions about my problem. Am I need to wait further until the star reaches the final phases (i.e. white dwarf phase) of its evolution? My aim is, the stars reach the white dwarf phase.
> 
> Best Regards
> Ebrahim Hassani
> 
> <Figure 2.png><Figure 1.PNG>