[Mesa-users] Problem at He flash when atm_T_tau_opacity = 'varying'

Tue Oct 4 01:40:35 UTC 2022

Dear All,

I'm trying to evolve a 1.0 solar mass star until the first thermal pulse using Ledoux criterium and atm_T_tau_opacity 'varying', with MESA r22.05.1. The inlist is copied below and next I copy the modifications I have tried, most of them were suggestions from https://github.com/MESAHub/mesa/issues/80/

My same initial inlist reaches the first thermal pulse without issues when initial mass is 1.4.
However, for 1 Msol the star gets cooler and dimmer instead of descending to the clump after reaching its peak giant luminosity. See red line in attached HR diagram.

Or, with some modifications (blue line, shifted to the right for clarity), the model reaches peak luminosity and continues with a zig-zag pattern perpendicular to the RGB until I kill the process.
The same happens with any of the other atm_T_tau_relation options: solar_Hopf, Krishna_Swamy, Trampedach_solar.

I don’t think there is a bug report for this, I could only find an email related to a test suite case titled “Problem with atm_T_tau_opacity at the helium flash stage” from February 2021.
Are there any other options I could try to get this model to the first thermal pulse?

Regards,
Claudia.

[cid:image002.png at 01D8D7E0.A4D92510][cid:image001.png at 01D8D7E0.9BBC1370]

------------------------

&star_job

    create_pre_main_sequence_model = .true.
    pre_ms_T_c = 5d5
    set_initial_number_retries = .false.
    initial_zfracs = 3 ! GS98_zfracs
    history_columns_file = 'my_history_columns.list'
    show_retry_counts_when_terminate = .true.
    show_timestep_limit_counts_when_terminate = .true.

/ ! end of star_job namelist

&eos
  ! eos options
  ! see eos/defaults/eos.defaults
/ ! end of eos namelist

&kap

    !opacities with GS98 abundances
    kap_file_prefix = 'gs98'
    kap_lowT_prefix = 'lowT_fa05_gs98'
    kap_CO_prefix = 'gs98_co'

    !CO enhanced opacities
    use_Type2_opacities = .true.
    Zbase = 0.02d0
/ ! end of kap namelist

&controls

    initial_mass = 1.00 ! in Msun units
    initial_z = 0.0187
    initial_y = 0.2718

  ! stop when the first thermal pulse occurs
    stop_at_phase_TP_AGB = .true.

    cool_wind_RGB_scheme = 'Reimers'
    cool_wind_AGB_scheme = 'Blocker'
    RGB_to_AGB_wind_switch = 1d-4
    Reimers_scaling_factor = 0.1
    Blocker_scaling_factor = 0.2
    max_wind = 1d-3

    D_SH_factor =  1.0
    D_SSI_factor = 1.0
    D_ES_factor =  1.0
    D_GSF_factor = 1.0
    D_DSI_factor = 1.0
    D_ST_factor = 0.0
    am_D_mix_factor = 0.033
    am_gradmu_factor = 0.05

    do_element_diffusion = .true.
    atm_option = 'T_tau'
    atm_T_tau_relation = 'Eddington'
    atm_T_tau_opacity = 'varying'

    okay_to_reduce_gradT_excess = .true.
    Pextra_factor = 2.0

    ! ####
    use_Ledoux_criterion = .true.
    alpha_semiconvection = 0.1
    thermohaline_coeff = 666.0

    mlt_option = 'Henyey'
    mixing_length_alpha = 1.90

    ! Core overshoot
    overshoot_scheme(1) = 'exponential'
    overshoot_zone_type(1) = 'any'
    overshoot_zone_loc(1) = 'core'
    overshoot_bdy_loc(1) = 'top'
    overshoot_f(1) = 0.016
    overshoot_f0(1) = 0.008
    overshoot_mass_full_off(1) = 1.10
    overshoot_mass_full_on(1) = 1.30

    ! shell overshoot
    overshoot_scheme(2) = 'exponential'
    overshoot_zone_type(2) = 'any'
    overshoot_zone_loc(2) = 'shell'
    overshoot_bdy_loc(2) = 'any'
    overshoot_f(2) = 0.0174
    overshoot_f0(2) = 0.0087

    energy_eqn_option = 'dedt'
    use_gold_tolerances = .true.

      delta_lg_XH_cntr_max = -1
      max_dq = 1d-3
      varcontrol_target = 1d-3
      max_allowed_nz = 50000

      delta_lgTeff_limit = 0.005
      delta_lgTeff_hard_limit = 0.01
      delta_lgL_limit = 0.02

  ! output
     history_interval = 1
     terminal_interval = 10
     write_header_frequency = 20
     photo_digits = 5
     photo_interval = 100
     write_profiles_flag = .false.

     star_history_name = 'history.data'

/ ! end of controls namelist
------------------------------------------------------------------------------------------------------

Modifications :

    change_initial_net = .true.
    new_net_name = 'mesa_49.net'
    change_v_flag = .true.
    new_v_flag = .true.

    use_T_tau_gradr_factor = .true. 
    atm_T_tau_max_steps = 2000 ! default is 500
    atm_T_tau_errtol = 1d-8    ! default is 1d-7
    timestep_factor_for_retries = 0.5
    use_dPrad_dm_form_of_T_gradient_eqn = .true.
    corr_coeff_limit = 1d-10
    use_gold2_tolerances = .true.
    gold_iter_for_resid_tol2 = 10
    gold_iter_for_resid_tol3 = 10
    gold_tol_residual_norm3 = 1d-6
    gold_tol_max_residual3 = 1d-3
    gold_solver_iters_timestep_limit = 20
    solver_iters_timestep_limit = 50
    scale_max_correction = 0.05d0
    convergence_ignore_equL_residuals = .false.
    delta_lgL_He_limit = 0.0001 ! Avoids running past the flash too fast
    correction_xa_limit = 3d-2
    fix_d_eos_dxa_partials = .true
    max_v_div_cs_for_convection = 100
    max_conv_vel_div_csound = 1d0 ! Limit convection speed
    use_gradT_actual_vs_gradT_MLT_for_T_gradient_eqn = .true.
    mesh_delta_coeff = 0.5
    time_delta_coeff = 0.5
    min_timestep_limit = 1d-8
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