[mesa-users] Slow evolution in 1.5 Msun model

Thu Oct 18 06:22:09 EDT 2012

Thanks Aaron for your prompt reaction.
Certainly, my MESA tracks extend to Teff < 3000 K after core He depletion
(using v. 4226 and earlier.). I have attached a sample HRD. This is also
consistent with the location of mid to late M-type stars (M5 in my case).

This is achieved without any witchcraft. My inlist has the Reimers mass
loss, the 'mesa' EOS, and the 'a09' kappa.
The only point that I am crying out for is the time cost of the run on a
12 node cluster.

With the same machine, say a 15 Msun star, reaches the RGB phase in two
hours. So, I am expecting nearly the same on the AGB phase. If each track
would take half or full day, then running a grid with say 60 tracks (my
case) needs over a month for one test :-0

Another point that confuses me is the large number of mesh points
(~24,000) by setting mesh_delta_coeff = 0.80, and keeping the rest as
defaults.

Thanks Aaron.
Ehsan.

> Hi Ehsan,
>
> You've certainly gone past central He depletion as your terminal output
> shows.  You may never achieve Teff < 3000 K for these stars unless you are
> using fancy mass loss and opacities.  If you just want central He
> depletion, use that alone to stop the calculation.  There is also
> something along the lines of "stop at 1st thermal pulse" that would take
> you a bit further.  How long it will take depends on your hardware, but it
> should not be more than ~5000 time steps.
>
> Aaron
>
>
>
> On Oct 18, 2012, at 7:23 PM, "Ehsan Moravveji" <moravveji at iasbs.ac.ir>
> wrote:
>
>>
>> Dear all,
>> I am running a grid of models of 1.5 to 2.5 Msun stars with v. 4589. The
>> star is supposed to start from the pre-MS phase, and stop after the core
>> He depletion once Teff < 3000.
>> This is supposed to be a trivial evolution as my experience with massive
>> tracks tell, in a sense that each model must finish in an hour or two.
>> However, it is over 12 hours that even the first model has not finished.
>> Here is the terminal output:
>>
>>
>>       step    lg_Tcntr    Teff       lg_LH     lg_Lnuc     Mass
>> H_rich     H_cntr     N_cntr     Y_surf     X_avg     eta_cntr
>> pts  retry
>>   lg_dt_yr    lg_Dcntr    lg_R       lg_L3a    lg_Lneu     lg_Mdot
>> H_poor     He_cntr    O_cntr     Z_surf     Y_avg     gam_cntr  iters
>> bckup
>>        age    lg_Pcntr    lg_L       lg_LZ     lg_Psurf    lg_Dsurf
>> He_poor    C_cntr     Ne_cntr    Z_cntr     Z_avg     v_div_cs
>> dt_limit
>> __________________________________________________________________________________________________________________________________________________
>>
>>      17250   8.032290   3384.687   3.079061   3.210327   1.347981
>> 0.819935   0.000000   0.000000   0.282155   0.427826  17.730055
>> 24225     81
>>   3.351565   6.104060   2.073604   2.480932   1.982266  -8.135194
>> 0.528046   0.000000   0.661732   0.014063   0.196686   4.907572      4
>>   16
>> 2.9688E+09  22.584314   3.218765   2.081776   3.222172  -8.111061
>> 0.449231   0.322686   0.001312  1.000E+00  3.755E-01  0.420E-06
>> varcontrol
>>
>>
>> I noticed that the number of mesh points in the model is exceedingly
>> high!
>> That might be a reason for this slow evolution. True?
>> I am sure that I never wanted such a fine mesh spacing as in from my
>> inlist:
>>
>>         mesh_delta_coeff = 0.8
>>         varcontrol_target = 1d-4    ! to adjust the time steps
>>
>> Is this typical of low-mass stars with mesa to take too long time to
>> finish?
>> Are there switches (except varcontrol_target) to speed up the evolution?
>> I believe there must be a way to reduce the time cost when running a
>> grid.
>>
>> Thanks
>> Ehsan.
>>
>>
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