[Mesa-users] Question regarding create_pre_main_sequence_model unused in binary mode

[Francis Timmes]

always include mesa-users in replies so that others can potentially help.


fxt



> On Dec 1, 2020, at 8:39 AM, Bear Ealeal <ealeal44 at yahoo.com> wrote:
> 
> 
> Thank you for the clarification.
> 
> I understand that MESA takes the “zams”  as initial conditions by default and there is no need to activate anything and it has nothing to do with the binary or single mode. Overriding it is possible in both.
> 
> However, there are two files in data/star_data/zams_models one ends with y28 and the other one with y98.
> 
> I understand that the y abundance is different, but from what I see the mass is different  (y28 has : M/Msun      1.2589254117941673E-01 and y98 has:  M/Msun      3.2499999999999964E+00) and also there is no mentioning of the time.
> 
> Can you clarify, how the file is being read and who decides which file is it, if nothing is giving in star_job? Moreover, who decides what is the initial time if create_pre_main_sequence_model  is not activated, is it initial_age = 0 as in the default?
> Thanks,
> 
> Ealeal
> 
>   
>  
> If I want to override the zams which is given as a default in MESA, i
> 
>  
> 
> 
> 
> On Monday, November 30, 2020, 06:40:42 AM GMT+2, Francis Timmes <fxt44 at mac.com> wrote:
> 
> 
> hi ealeal,
> 
> this is not a single / binary model issue per se.
> 
> http://mesa.sourceforge.net/star_job_defaults.html#starting_model
> 
> by default, a zams starting model of the specified mass is loaded at the start.
> one can override this default by using, for example, create_pre_main_sequence_model.
> 
> at the beginning of a run mesa can enter a "relaxation" mode to find a suitable model. 
> this is a pseudo-evolution that changes a model (say the mass or angular momentum to be more concrete) 
> to reach a user specified target. this relaxation commonly uses a "timestep" of 1e5 yr. 
> once a suitable model is found, the pseudo-evolution relaxation terminates and the full evolution begins.
> 
> fxt
> 
> 
> 
> 
> 
> > On Nov 29, 2020, at 9:47 AM, Bear Ealeal via Mesa-users <mesa-users at lists.mesastar.org> wrote:
> > 
> > Binary mode vs. single mode
> > 
> > In the single mode when evolving a star from the beginning , examples in test_suite use create_pre_main_sequence_model=.true. or a loaded file. However in the binary mode examples do not use this option. However, the code starts at some point and evolves.
> > 
> > For example in evolve_both_stars in test_suite the option of create_pre_main_sequence_model is not activated, however when running the example it starts at 1e5yr. From where does it get the data to start? what are the initial conditions for this option?
> > 
> > Thanks,
> > 
> > Ealeal
> 
> > 
> > 
> > 
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> 
> >