[Mesa-users] Cooling a CO White Dwarf

Charlie Sharpe charliesharpe2101 at gmail.com
Fri May 28 00:58:10 UTC 2021


Hello,

I have been trying to model a solar mass star that is dominated by Helium
(~ 75% He). I have been able to achieve this by simply modifying
the 1M_pre_ms_to_wd test suite case. The star goes through all stages of
evolution, eventually reaching a white dwarf, but the code then runs into
convergence issues when the surface temperature reaches about 6000 K (See
attached TRho_profile_freeze.ong). I have also attached the corresponding
element composition (Abundance.png). The same thing happens, but at higher
temperatures, when I use higher masses (e.g. 1.5M, 2M, etc.).

I need to see the star cool to a surface temperature of 3500K-4000K (The
point where photosynthesis can no longer occur at an efficient rate).

In an attempt to circumvent this, I have loaded the 6000K model but changed
the composition to be uniform and consist of 50% c12 and 50% o16. I thought
this might allow it to cool further and hopefully reach a sub 4000K surface
temperature. I have attached the inlist I used to do this
(inlist_to_wd_uni_comp) and the composition file (CO_comp.obj). However,
when I do this, I get the following terminal output (below). I have also
tried doing the same thing using set_uniform_initial_composition = .true.
and initial_zfracs = 0, instead but this just gives the same error. Is
there a better way to do this and/or a better way to allow the white dwarf
to cool further?

Thanks in advance,

Regards,
Charlie

DATE: 2021-05-28

TIME: 10:50:09

 version_number 15140

 read inlist_to_wd_uni_comp

load saved model final.mod


 net name co_burn.net

 kap_option gs98

 kap_CO_option gs98_co

 kap_lowT_option lowT_fa05_gs98

                                        OMP_NUM_THREADS           4



__________________________________________________________________________________________________________________________________________________


       step    lg_Tmax     Teff     lg_LH      lg_Lnuc     Mass       H_rich
    H_cntr     N_cntr     Y_surf   eta_cntr   zones  retry

   lg_dt_yr    lg_Tcntr    lg_R     lg_L3a     lg_Lneu     lg_Mdot
He_core    He_cntr    O_cntr     Z_surf   gam_cntr   iters

     age_yr    lg_Dcntr    lg_L     lg_LZ      lg_Lphoto   lg_Dsurf   C_core
    C_cntr     Ne_cntr    Si_cntr  v_div_cs       dt_limit

__________________________________________________________________________________________________________________________________________________


 retry    1616

                           1st model retry log10(dt/yr)
6.7599132073123602D+00

 retry    1616

                           1st model retry log10(dt/yr)
6.4588832116483790D+00

 retry    1616

                           1st model retry log10(dt/yr)
6.1578532159843977D+00

 retry    1616

                           1st model retry log10(dt/yr)
5.8568232203204165D+00

 retry    1616

                           1st model retry log10(dt/yr)
5.5557932246564352D+00

 retry    1616

                           1st model retry log10(dt/yr)
5.2547632289924540D+00

 retry    1616

                           1st model retry log10(dt/yr)
4.9537332333284736D+00

 retry    1616

                           1st model retry log10(dt/yr)
4.6527032376644923D+00

 retry    1616

                           1st model retry log10(dt/yr)
4.3516732420005111D+00

 retry    1616

                           1st model retry log10(dt/yr)
4.0506432463365298D+00

 retry    1616

                           1st model retry log10(dt/yr)
3.7496132506725486D+00

 retry    1616

                           1st model retry log10(dt/yr)
3.4485832550085673D+00

 retry    1616

                           1st model retry log10(dt/yr)
3.1475532593445861D+00

 retry    1616

                           1st model retry log10(dt/yr)
2.8465232636806048D+00

 retry    1616

                           1st model retry log10(dt/yr)
2.5454932680166240D+00

 retry    1616

                           1st model retry log10(dt/yr)
2.2444632723526428D+00

 retry    1616

                           1st model retry log10(dt/yr)
1.9434332766886615D+00

 retry    1616

                           1st model retry log10(dt/yr)
1.6424032810246803D+00

 retry    1616

                           1st model retry log10(dt/yr)
1.3413732853606992D+00

 retry    1616

                           1st model retry log10(dt/yr)
1.0403432896967180D+00

 retry    1616

                           1st model retry log10(dt/yr)
7.3931329403273682D-01

 retry    1616

                           1st model retry log10(dt/yr)
4.3828329836875568D-01

 retry    1616

                           1st model retry log10(dt/yr)
1.3725330270477448D-01

 retry    1616

                           1st model retry log10(dt/yr)
-1.6377669295920669D-01

 retry    1616

                           1st model retry log10(dt/yr)
-4.6480668862318786D-01

 retry    1616

                           1st model retry log10(dt/yr)
-7.6583668428716900D-01

 retry    1616

                           1st model retry log10(dt/yr)
-1.0668666799511501D+00

 retry    1616

                           1st model retry log10(dt/yr)
-1.3678966756151314D+00

 retry    1616

                           1st model retry log10(dt/yr)
-1.6689266712791127D+00

 retry    1616

                           1st model retry log10(dt/yr)
-1.9699566669430937D+00

 retry    1616

                           1st model retry log10(dt/yr)
-2.2709866626070747D+00

 retry    1616

                           1st model retry log10(dt/yr)
-2.5720166582710560D+00

 retry    1616

                           1st model retry log10(dt/yr)
-2.8730466539350372D+00

 retry    1616

                           1st model retry log10(dt/yr)
-3.1740766495990185D+00

 retry    1616

                           1st model retry log10(dt/yr)
-3.4751066452629997D+00

 retry    1616

                           1st model retry log10(dt/yr)
-3.7761366409269810D+00

 retry    1616

                           1st model retry log10(dt/yr)
-4.0771666365909622D+00

 retry    1616

                           1st model retry log10(dt/yr)
-4.3781966322549426D+00

 retry    1616

                           1st model retry log10(dt/yr)
-4.6792266279189239D+00

 retry    1616

                           1st model retry log10(dt/yr)
-4.9802566235829051D+00

 retry    1616

                           1st model retry log10(dt/yr)
-5.2812866192468864D+00

 retry    1616

                           1st model retry log10(dt/yr)
-5.5823166149108676D+00

 retry    1616

                           1st model retry log10(dt/yr)
-5.8833466105748489D+00

 retry    1616

                           1st model retry log10(dt/yr)
-6.1843766062388301D+00

 retry    1616

                           1st model retry log10(dt/yr)
-6.4854066019028114D+00

 retry    1616

                           1st model retry log10(dt/yr)
-6.7864365975667926D+00

 retry    1616

                           1st model retry log10(dt/yr)
-7.0874665932307739D+00

 retry    1616

                           1st model retry log10(dt/yr)
-7.3884965888947551D+00

 retry    1616

                           1st model retry log10(dt/yr)
-7.6895265845587364D+00

 retry    1616

                           1st model retry log10(dt/yr)
-7.9905565802227176D+00

 retry    1616

                           1st model retry log10(dt/yr)
-8.2915865758866989D+00

 retry    1616

                           1st model retry log10(dt/yr)
-8.5926165715506801D+00

 retry    1616

                           1st model retry log10(dt/yr)
-8.8936465672146596D+00

 retry    1616

                           1st model retry log10(dt/yr)
-9.1946765628786409D+00

 retry    1616

                           1st model retry log10(dt/yr)
-9.4957065585426221D+00

 retry    1616

                           1st model retry log10(dt/yr)
-9.7967365542066034D+00

 retry    1616

                           1st model retry log10(dt/yr)
-1.0097766549870585D+01

 retry    1616

                           1st model retry log10(dt/yr)
-1.0398796545534566D+01

 retry    1616

                           1st model retry log10(dt/yr)
-1.0699826541198547D+01

 retry    1616

                           1st model retry log10(dt/yr)
-1.1000856536862528D+01

 retry    1616

                           1st model retry log10(dt/yr)
-1.1301886532526510D+01

 retry    1616

                           1st model retry log10(dt/yr)
-1.1602916528190491D+01

 retry    1616

                           1st model retry log10(dt/yr)
-1.1903946523854472D+01

 retry    1616

                           1st model retry log10(dt/yr)
-1.2204976519518453D+01

 retry    1616

                           1st model retry log10(dt/yr)
-1.2506006515182435D+01

 retry    1616

                           1st model retry log10(dt/yr)
-1.2807036510846416D+01

 retry    1616

                           1st model retry log10(dt/yr)
-1.3108066506510397D+01

 retry    1616

                           1st model retry log10(dt/yr)
-1.3409096502174378D+01

 retry    1616

                                                     dt
6.1514495879130789D-07

                                     min_timestep_limit
9.9999999999999995D-07


 stopping because of problems dt < min_timestep_limit



terminated evolution: cannot find acceptable model


termination code: min_timestep_limit
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