[mesa-users] CO cores

[Bill Paxton]

Hi Tug,

On Jul 22, 2013, at 5:46 PM, Tuguldur Sukhbold wrote:

> Bill, 
> 
> thanks a lot for these! If you remember, couple of months ago we had some trouble running bare CO cores until preSN. Eventually we figured out few cases, but they were producing an iron core much smaller than KEPLER's. We thought differences in the codes during Si burning might be affecting the preSN results, so we decided to run MESA models only until core oxygen depletion.

It is only recently that I've been able to make these work all the way.  In fact they might not work in the release from last week!
I'll provide an update version for people who'd like to play with this.

> 
> But these plots are very interesting. With KEPLER we get iron core masses of:
> 
> CO core mass	Iron core mass at preSN
> 3				1.57
> 15				1.89
> 
> Eyeballing from your figures these numbers look very close. What composition did you use for 15Msun core? I hope you used the equation I provided in the original email…

I got 1.55 for the 3M case and 1.86 for the 15.   pretty close indeed!   And I had no idea what your values were.   nice.

what did you get for center Ye?  I got 0.428 for the 3M and 0.434 for the 15.
I haven't made a careful comparison of how the Ye's change as I vary the net.
It will be interesting to see what Ye KEPLER gets for these.

I used the same composition and same mixing as you did, and the same c12(a,g)o16 rate

         ! C/O MIX
         ! set target uniform composition for relax_initial_to_xaccrete
         num_accretion_species = 2
         accretion_species_id(1) = 'c12'
         accretion_species_xa(1) = 0.2145d0
         accretion_species_id(2) = 'o16'
         accretion_species_xa(2) = 0.7855d0

         mixing_length_alpha = 1.0
         use_Henyey_MLT = .false.
         
         use_Ledoux_criterion = .true.
         alpha_semiconvection = 0.1
         
         thermo_haline_coeff = 0d0

         overshoot_f_above_nonburn = 0.05
         overshoot_f_above_burn_h = 0.0
         overshoot_f_above_burn_he = 0.0
         overshoot_f_above_burn_z = 0.0
         
         overshoot_f_below_nonburn = 0.05
         overshoot_f_below_burn_h = 0.0
         overshoot_f_below_burn_he = 0.0
         overshoot_f_below_burn_z = 0.0

      set_rate_c12ag = 'Buchmann'
      num_special_rate_factors = 1
      reaction_for_special_factor(:) = 'r_c12_ag_o16'
      special_rate_factor(1) = 1.2


> We have been running 100s of full star and bare core models. Before we finish analyzing them and writing the paper, a new version of MESA comes up offering better results. This happened twice already, I guess now it is the 3rd time. :-D

You have to move fast!

cheers,
bill