[mesa-users] cool_brown_dwarf

[Aaron Dotter]

Hi Tahere,

>From controls.defaults, below are the default settings.

         !### logQ_limit

         ! logQ = logRho - 2*logT + 12.
         ! stop if logQ at any zone is larger than this limit.
         ! 5 is a reasonable limit for the current mesa/eos.

      logQ_limit = 5d0


and

         !### max_model_number
         ! The code will stop when it reaches this model number.
         ! Negative means no maximum.

      max_model_number = -1


I would suggest not to change logQ_limit unless you are very familiar with
the MESA EOS.

In the cool brown dwarf inlist, max_model_number = 4000 but you should feel
free to increase it.


I hope this is helpful.

Cheers,
Aaron



On Tue, Nov 15, 2016 at 4:41 AM, tahere parto <tahereparto at gmail.com> wrote:

> Dear mesa users,
>
> I'm trying to implement MESA to find a minimum mass for ZAMS
> (the minimum mass for a star which can develop a hot core to be able
> to burn hydrogen as the main source of energy and start main
> sequence stage). as you recommended me before, I use
> \star\test_suite\cool_brown_dwarf for this purpose.
>
> When I run the code without any change, after a while it stops with this
> termination code: max_age all result are okay .
>
> Then I change the mass from 0.064 to 0.08 and run the code for each mass
> and I noticed some problems.
> for some masses the code encountered a convergence problem and stops with
> this error:
>
> hydro_newton_step failed to converge
> stopping because of convergence problems dt < min_timestep_limit
> terminated evolution: convergence problems
>
> I change some conditions in controls and star_job like initial dt,
> years_for_initial_dt, varcontrol_target ,max_age and I also change
> mesh_delta_coeff=0.5 to mesh_delta_coeff=0.1.
>
> &star_job
>
> !set_initial_dt = .true.
>
> !years_for_initial_dt = 1d-7
>
>
> &controls
>
> !varcontrol_target = 3d-5
>
> mesh_delta_coeff = 0.1
>
> !max_age = 10.1d9
>
> Then convergence problem doesn't happen and The code stops with one of
> these termination code depend on which mass I use. For some masses I
> encountered ( Log_Q limit failed ) message and for some masses (max model
> number failed) message.
> Here are my questions:
>
> Is it okay to change those conditions and the code stops running because
> of reaching max model number failed?
>
> How can I handle log_Q limit failed?
>
> Thank you in advance,
>
> Tahere
>
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