[Mesa-users] Setting Multiple Element Abundances

[Rob Farmer]

Hi
I agree with Frank your best bet is to explicitly set all the abundances in
one go. You can do this with:

https://docs.mesastar.org/en/latest/reference/star_job.html#file-for-uniform-xa

Where you provide a file with each isotope in your network and the starting
abundances you want.

Rob


On Wed, 10 Mar 2021 at 06:10, Francis Timmes via Mesa-users <
mesa-users at lists.mesastar.org> wrote:

> hi andrew,
>
> set_abundance, set_initial_abundance, chem_name, and new_frac are scalars
> not vectors.
> thus, after the inlist is read only the last setting holds. this means
> only 1 isotope
> can be changed by this method with one inlist.
>
> to demonstrate, i copied basic_ba.net to basic_ba_new.net
> and uncommented sr88 and pb208 in basic_ba_new.net.
>
> in inlist_accrete
>
>       set_abundance = .true.
>       set_initial_abundance = .true.
>       chem_name = 'ba138'
>       new_frac = 1.11d-16
>
>       set_abundance = .true.
>       set_initial_abundance = .true.
>       chem_name = 'pb208'
>       new_frac = 2.22d-16
>
>       set_abundance = .true.
>       set_initial_abundance = .true.
>       chem_name = 'sr88'
>       new_frac = 3.33d-16
>
> upon running 12115 the network was expanded from the 9 isotopes in
> start.mod
> to the desired 11 isotopes, and the single output line
>
> set_abundance of sr88   3.3299999999999999E-016           1         931
>
> confirms that only the last setting is applied.
>
> one can also see the scalar not vector nature of these settings in the
> source code
> beginning at line 2435 in $MESA_DIR/star/job/run_star_support.f90
>
>
> i was able to achieve the desired result of changing all 3 isotopes by a
> kludge.
> i changed one isotope, took 1 tiny timestep, and saved a new mod file.
> starting from this new mod file, repeat the process for the second isotope.
> and finally once more for the third isotope. e.
>
> a better solution would be to make these settings vectors such that
> an arbitrary number of isotopes can be modified with one inlist.
>
> fxt
>
>
>
>
>
>
>
>
> > On Mar 9, 2021, at 12:10 PM, Andrew Nine via Mesa-users <
> mesa-users at lists.mesastar.org> wrote:
> >
> > Hello all,
> >
> > I'm running evolutionary models of stars after they accrete mass from an
> AGB donor in r12115. When I try to set the accreting star's initial
> abundances of Ba138, Pb208, and Sr88 to zero, two of the three will take on
> some default value that is not zero. Here's what I have in my inlist:
> >
> >       change_net = .true.
> >       new_net_name = 'basic_ba.net'
> >
> >       set_abundance = .true.
> >       set_initial_abundance = .true.
> >       chem_name = 'ba138'
> >       new_frac = 0
> >
> >       !set_abundance = .true.
> >       !set_initial_abundance = .true.
> >       !chem_name = 'pb208'
> >       !new_frac = 0
> >
> >       !set_abundance = .true.
> >       !set_initial_abundance = .true.
> >       !chem_name = 'sr88'
> >       !new_frac = 0
> >
> > I have also attached full copies of my inlist, reaction net, starting
> model, and run_star_extras. Is there a way to set all three initial
> abundances to zero?
> >
> > Best,
> >
> > Andrew Nine
> > <basic_ba.net
> ><inlist_accrete><start.mod><run_star_extras.f>_______________________________________________
> > mesa-users at lists.mesastar.org
> > https://lists.mesastar.org/mailman/listinfo/mesa-users
> >
>
> _______________________________________________
> mesa-users at lists.mesastar.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users
>
>
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