[mesa-users] Evolution of binary stars, problem to converge

jean-baptiste vielfaure jean.baptiste.vielfaure at gmail.com
Wed Aug 3 08:30:26 EDT 2016


Hello everyone,

I am using the version 8118 of MESA to evolve a binary system composed of
an intermediate massive star of 7.0 and one of 5.9 Msun, from ZAMS to white
dwarf and neutron star binary. I know I won't reach this stage of evolution
because it's expected that 4 mass transfers occur, with the third one in a
common envelope evolution (CEE). So my goal is to reach this step as near
as possible to have the features of each star at this moment.
The problem is that MESA slows down and stops at the end of the second mass
transfer from the primary to the secondary, so far before CEE. The reason
is problem convergence, dt becomes too small.

The white dwarf state for the primary seems to be reached and the radius of
the secondary is far to be roche lobe value.

The informations dislayed on the screen are : *dt_limit : retry or max
increase*
and
*hydro_newton_step failed to converge*

 I attached my inlist_project file in which I consider for each star :

















































*    kappa_file_prefix = 'gs98'    change_initial_net = .true.
new_net_name = 'o18_and_ne22.net <http://o18_and_ne22.net>'
use_Type2_opacities = .true.    Zbase = 0.02d0    varcontrol_target = 5d-4
  mesh_delta_coeff = 1.5    am_nu_visc_factor = 0    am_D_mix_factor =
0.0333333333333333d0    D_DSI_factor = 0    D_SH_factor = 1    D_SSI_factor
= 1    D_ES_factor = 1    D_GSF_factor = 1    D_ST_factor = 1
mixing_length_alpha = 1.7     use_Ledoux_criterion = .true.
alpha_semiconvection = 0.01     thermohaline_coeff = 2
overshoot_f_above_nonburn_core = 0.02   overshoot_f0_above_nonburn_core =
0.004   overshoot_f_above_burn_h_core = 0.02
overshoot_f0_above_burn_h_core = 0.004   overshoot_f_above_burn_he_core =
0.02   overshoot_f0_above_burn_he_core = 0.004
overshoot_f_above_burn_z_core = 0.02   overshoot_f0_above_burn_z_core =
0.004      cool_wind_full_on_T = 1d6      cool_wind_full_off_T = 2d6
cool_wind_RGB_scheme = 'Reimers'      cool_wind_AGB_scheme = 'Blocker'
RGB_to_AGB_wind_switch = 1d-4      Reimers_scaling_factor = 0.5d0
Blocker_scaling_factor = 0.1d0*
and for the binary evolution :
















*   fr = 0.05   fr_limit = 1d-2   limit_retention_by_mdot_edd = .false.
max_tries_to_achieve = 50  do_wind_mass_transfer_1 = .true.
do_wind_mass_transfer_2 = .true.    do_initial_orbit_sync_1 = .true.
do_initial_orbit_sync_2 = .true.   do_tidal_circ = .true.  do_tidal_sync =
.true.*
I attached inlist files and models for the 2 stars, at model number 27400.
At this moment the evolution is really slow, so if you have an idea to make
MESA go faster or to avoid the convergence problem that occurs usually it
will be fantastic.


Thanks for your help.
Jean-Baptiste VIELFAURE
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