[Mesa-users] Reproducing Paxton et al. 2013 fig. 1

[Francis Timmes]

hi emily,

yes, this is a known issue. see this thread

https://lists.mesastar.org/pipermail/mesa-users/2024-March/015070.html

and this potential workaround

https://lists.mesastar.org/pipermail/mesa-users/2024-April/015133.html

some preliminary mesa-dev investigations suggested the phenomena may be due to changes since 2013 how the low temperature eos is handled. if you find the problem persists, perhaps file an issue on mesa github https://github.com/MESAHub/mesa .

fxt





> On Jul 10, 2024, at 8:24 AM, Emily Sandford via Mesa-users <mesa-users at lists.mesastar.org> wrote:
> 
> Hello,
> 
> I'm a new MESA user, attempting to use r24.03.1 to model brown dwarf and giant planet evolution. As a first step I want to reproduce the models plotted in Paxton et al. 2013 figure 1, which are initiated with create_initial_model with radius equal to 5 R_J and masses ranging from 0.2 to 20 M_J, and then evolved for 20 Gyr.
> 
> The only controls enumerated in the paper are:
> &star_job
>   create_initial_model = .true.
>   mass_in_gm_for_create_initial_model = 3.7972d31  ! 20 m_jupiter;  m_jupiter = 1.8986d30
>   radius_in_cm_for_create_initial_model = 3.596d10 ! 5 r_jupiter; r_jupiter = 7.192d9
> / ! end of star_job namelist
> 
> &eos
>   eosDT_file_prefix = 'mesa' ! replaces deprecated eos_file_prefix = 'mesa', as I understand it
> / ! end of eos namelist
> 
> &kap
>   Zbase = 0.02d0             ! not mentioned explicitly in Paxton et al. 2013, but now seems to be necessary
>   kap_file_prefix = 'gs98'
>   kap_lowT_prefix = 'lowT_Freedman11'
> / ! end of kap namelist
> 
> &atm
>   which_atm_option = 'simple_photosphere'
> / ! end of atm namelist
> 
> &controls
>   initial_y = 0.27d0
>   initial_z = 0.02d0
>   mixing_length_alpha = 2.0d0
>   max_age = 2.0d10
> / ! end of controls namelist
> 
> This works fine for initial mass 20 M_J; however, it fails almost immediately for initial mass <= 14 M_J (the initial model is created, but then the evolution stalls at age ~a few years). I looked at the make_brown_dwarf test suite example for inspiration, and found that adding
> 
> convergence_ignore_equL_residuals = .true.
> 
> allows models with initial masses down to 6.9 M_J to evolve for the full 20 Gyr without problems. However, for initial masses <= 4.8 M_J, the evolution stalls once again (at late ages--for the 4.8 M_J model, it's at 12.4 Gyr), and I don't know how to fix this. I've tried turning on the other controls used in make_brown_dwarf (mlt_make_surface_no_mixing = .false. , make_gradr_sticky_in_solver_iters = .true. , energy_eqn_option = 'dedt'), but none of them have any effect. I've also played around with the make_planets test suite example, turning off the step where an inert core is added, but with no success.
> 
> The one thing that worked for the 4.8 M_J model was to adjust the initial radius downward to 2 R_J, but then that choice of radius also fails for initial masses <= 3.4 M_J (and I'm hoping there's an easier way forward than to keep hand-tuning the initial radius for every new choice of initial mass).
> 
> Does anyone have advice for how to make progress from here, ideally in a way that allows me to run a suite of models at different initial masses but with the same initial radius, as with the models plotted in Paxton+2013? I'm happy to provide more detailed debugging information if it's helpful, but given that these models have successfully been run before, I'm hoping it's just a matter of choosing the right inlist settings.
> 
> Thanks!
> Emily Sandford
> sandford at strw.leidenuniv.nl
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>