[mesa-users] Problem evolving a donor star

[Odette Toloza]

Hi Mesa-users

I am relatively new with MESA, and I am having troubles with evolving a
binary system containing a evolved donor. Based on the
binary_donor_only_implicit_mdot suite test we have tried to evolve white
dwarf of 0.8 solar masses together with a donor star of 1 solar mass. But
first at all we created a model for the donor starting from the ZAMS and
stopping the evolution controlling the core composition.


xa_central_lower_limit_species(1) = 'h1'
xa_central_lower_limit(1) = 0.5  ! or less evolved 0.8


When we include this model on the binary_donor_only_implicit_mdot suite
test and we make sure that with an orbital period of 0.6d the system is out
of contact. It starts running but as soon as the mass transfer starts MESA
stops. The first amount of mass transferred is too high and MESA collapses
returning negatives values for angular momentum (STOP bad
angular_momentum_j).

the orbit shrinks quite fast since the jump of (r-rl)/rl is too abrupt
before the last step is 6.421261633E-01 and in the last step is
-1.409570580E-02, as well as lg_mdot, from -2.062847169E+01 to
-9.900000000E+01

We have considered all the mechanisms of jdot,

   do_jdot_gr = .true.
   do_jdot_ml = .true.
   do_jdot_ls = .true.
   do_jdot_missing_wind = .true.
   do_jdot_mb = .true.



For some reason MESA complains with the inclusion of an evolved donor. To
make sure that we are not making any mistake during the inclusion of the
model, we created another evolved model this time with 80% of hydrogen in
the core. When we include it, MESA runs without problems.


Does anyone have any idea why this could be happen?

Cheers,
Odette Toloza
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