[Mesa-users] Having difficulty to evolve low mass stars

Wed Mar 4 17:57:07 UTC 2026

Hi Ebraheem,

Thank you for your guidance. I will work on incorporating the changes
suggested by you and will share the progress once it is made.

I will also make sure to CC all members in future communications.

Additionally, could you please suggest some good resources or methods to
get a better hold of MESA commands? I am currently struggling to learn and
navigate them.

Regards,
Sanskar

On Wed, 4 Mar 2026, 11:21 pm Farag, Ebraheem, <ebraheem.farag at yale.edu>
wrote:

> Hello Sanskar, (please keep mesa-users cc'd in your replies)
>
> I would recommend looking at what is done inside $MESA_DIR/star/test_suite/
> *1M_pre_ms_to_wd.*
>
> From my end, your model should converge through the He-flash, simply by
> adding the following control to your inlist.
>
> ! Added solver stability to late newton iterations, by ensuring that cells
> that become radiative during last iterations, remain radiative.
> make_gradr_sticky_in_solver_iters = .true.
>
> I tested by simply pasting this line into the inlist file you shared and
> restarting from the 'standard_start_he_core_flash.mod' found inside
> $MESA_DIR/star/test_suite/*1M_pre_ms_to_wd*, and the model evolves
> through the flash to core-He depletion with no issues.
>
> If you are curious exactly what this control is doing, I would recommend
> grepping the source code in $MESA_DIR/star/private, so see what it does.
>
> In the past, it was common to set : convergence_ignore_equL_residuals =
> .true. , to get through the flash, as is done in the test_suite, however
> with enhancements to the solver available in the r25.12.1 and onward, I
> prefer my  former suggestion, and keeping convergence_ignore_equL_residuals
> = .false. . You're free to experiment with both options.
>
> You might also benefit from Ana's suggestion to lower mesh_delta_coeff, to
> spatially resolve your stellar model, and with some additional time
> resolution for helium burning :
>
>          ! These controls are the bare minimum.
> delta_lgL_He_limit = 1d-2 ! Or lower
>           mesh_delta_coeff = 1d0
>
>
> -EbF
> ------------------------------
> *From:* Sanskar <sanskarchauhantifr at gmail.com>
> *Sent:* Wednesday, March 4, 2026 12:15 PM
> *To:* Farag, Ebraheem <ebraheem.farag at yale.edu>
> *Subject:* Re: [Mesa-users] Having difficulty to evolve low mass stars
>
> I'm using mesa version r25.12.1
>
> On Wed, 4 Mar 2026, 10:43 pm Farag, Ebraheem, <ebraheem.farag at yale.edu>
> wrote:
>
> Hello Sanskar, what version of mesa are you using?
>
> -EbF
> ------------------------------
> *From:* Mesa-users <mesa-users-bounces at lists.mesastar.org> on behalf of
> Sanskar via Mesa-users <mesa-users at lists.mesastar.org>
> *Sent:* Wednesday, March 4, 2026 12:07 PM
> *To:* Mesa-users <mesa-users at lists.mesastar.org>
> *Subject:* [Mesa-users] Having difficulty to evolve low mass stars
>
> Hello,
>
>  I am a first  year PhD student using MESA for first time. I am having
> difficulty evolving 1M solar mass star to its end stage (white dwarf). The
> evolution is not getting pass the helium flash point and the solver shows
> error of min tilmestep reached(10^-13).I  am also attaching the inlist  for
> this.
>
> ! inlist to evolve a 1 solar mass star
>
>
> &star_job
>
>    create_pre_main_sequence_model = .true.
>
>    change_net=.true.
>    new_net_name='pp_and_cno_extras.net'
>
>    ! save a model at the end of the run
>    save_model_when_terminate = .true.
>    save_model_filename = '2M_final.mod'
>
>    ! display on-screen plots
>    pgstar_flag = .true.
>
> /
>
>
> &eos
>
> /
>
>
> &kap
>
>    use_Type2_opacities = .true.
>    Zbase = 0.014
>
> /
>
>
> &controls
>
>
>    ! starting specifications
>    initial_mass =1 ! in Msun units
>    initial_z = 0.014
>
>    ! when to stop
>    fe_core_infall_limit=1d8
>    log_L_lower_limit=-1.5
>
>   ! xa_central_lower_limit_species(1) = 'o16'
>   ! xa_central_lower_limit(1) = 1d-3
>
>    max_model_number=100000
>
>    ! wind
>    Reimers_scaling_factor = 0.7
>    Blocker_scaling_factor=1.0
>    ! atmosphere
>
>    ! rotation
>
>    ! element diffusion
>
>    ! mlt
>
>    ! mixing
>    mixing_length_alpha = 1.8
>    use_Ledoux_criterion = .true.
>
>    ! Semiconvection
>    alpha_semiconvection = 1.0
>
>    ! Thermohaline
>    thermohaline_coeff = 1.0
>
>    overshoot_scheme(1) = 'step'
>   overshoot_zone_type(1) = 'burn_H'
>   overshoot_zone_loc(1) = 'core'
>   overshoot_bdy_loc(1) = 'top'
>   overshoot_f(1) = 0.345
>   overshoot_f0(1) = 0.01
>
>   ! Also overshoot above He burning core
>   overshoot_scheme(2) = 'step'
>   overshoot_zone_type(2) = 'burn_He'
>   overshoot_zone_loc(2) = ‘core'
>   overshoot_bdy_loc(2) = 'top'
>   overshoot_f(2) = 0.1
>   overshoot_f0(2) = 0.01
>
>    ! timesteps
>    varcontrol_target = 1d-2
>   max_timestep_factor = 1.1
>   delta_lgL_limit = 0.005
>   delta_lgTeff_limit = 0.005
>   delta_lgRho_cntr_limit = 0.025
>   delta_lgT_cntr_limit = 0.01
>   delta_lg_XH_cntr_limit = 0.005
>   delta_lg_XHe_cntr_limit = 0.005
>   delta_lg_XC_cntr_limit = 0.005
>   delta_lg_XNe_cntr_limit = 0.005
>   delta_lg_XO_cntr_limit = 0.005
>   delta_lg_XSi_cntr_limit = 0.005
>
>   delta_lgL_limit=0.01
>   delta_lgteff_limit=0.01
>
>    min_timestep_limit = 1d-12
>
>    ! mesh
>    mesh_delta_coeff = 2.0
>    max_allowed_nz = 10000
>
>    ! solver
>    ! options for energy conservation (see MESA V, Section 3)
>     energy_eqn_option = 'eps_grav'
>     use_gold_tolerances = .true.
>
>    delta_lgR_limit=0.1
>
>    ! output
>
> /
>
>
>
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