[mesa-users] Question about abundances in the 1 Msun test problem

[Manos Chatzopoulos]

Dear all,

  I have a question with regards to the initial abundances of the solar 
(1M_pre_ms_to_wd) problem in the test_suite. Basically
the issue is that the initial surface abundance of Mg24 should always be 
smaller than that of Ne20. I do know from previous
communication that this is an issue with the size of the network used in 
MESA but it actually does not solve the problem.
  If one just runs the test problem as it is the Mg24/Ne20 ratio is 
wrong. Even if I switch to using approx21.net instead of
the default (in the test inlist_1.0) o18_and_ne22.net the ratio is still 
wrong. Now when I add the following lines in the inlist_1.0:

       set_uniform_initial_composition = .true.
       initial_zfracs = 3
       initial_h1 = 6.9979637695268626D-01
       initial_h2 = 0
       initial_he3 = 2.7973106548401051D-05
       initial_he4 = 2.7970309237746210D-01

and I run with the original o18_and_ne22.net the ratio is still wrong. I 
only get the correct ratio of Mg/Ne when I run
with approx21.net AND the above lines included in the inlist.

  My question is why when using a large network from the beginning of 
the run (that includes both isotopes, like approx21.net) does
not assign the correct solar abundance ratios for these isotopes in the 
model? Why are those lines of code needed for this and it
is not done by default since I input inital_z = 0.02d0?

Regards and thank you in advance,

Manos