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

Wed Mar 4 17:51:10 UTC 2026

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<mailto: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<mailto:mesa-users-bounces at lists.mesastar.org>> on behalf of Sanskar via Mesa-users <mesa-users at lists.mesastar.org<mailto:mesa-users at lists.mesastar.org>>
Sent: Wednesday, March 4, 2026 12:07 PM
To: Mesa-users <mesa-users at lists.mesastar.org<mailto: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<http://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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