[Mesa-users] A question about MESA for pre-main-sequence evolution

[Meridith Joyce]

Hi LiJiaxun,

My recommendations come from an inlist I used with version 15140 (meaning
some things might be different from your version):

Have a look at the &star_job controls. I have the following configuration
for setting deuterium:
      set_abundance = .true.
      set_initial_abundance = .true.
      chem_name = 'h2'
      new_frac = 2e-5

For pre-main sequence evolution of low-mass stars, it is also important to
set
    pre_ms_relax_to_start_radiative_core = .false.

Also ensure that deuterium is included in the nuclear network you use.

In my opinion, it is also better to set your hydrogen and helium abundances
with &star_job parameters rather than &controls parameters. Setting Zbase
in &kap to your Z value
Z = 1 - (X + Y + deuterium etc )
is generally safe.

Hope that helps,


On Thu, Oct 20, 2022 at 4:35 PM LiJiaxun via Mesa-users <
mesa-users at lists.mesastar.org> wrote:

> Hi,
> My name is Li Jiaxun. I am a student who have just started to learn MESA.
> I want to calculate low mass pre-main-sequence star to main-sequence. So I
> choose the $MESA_DIR$/star/test_suite/make_zams_low_mass for template.
> In order to calculate metal abundance Z=0.019, Helium abundance Y=0.275
> and M=0.085 M_sun or M=0.2 M_sun, I only changed the following Settings
> "
> Zbase = 0.019d0
> "
> in inlist_zams, &kap, and
> "
> initial_mass = 0.085 !or 0.2
> initial_z = 0.019d0
> initial_y = 0.275
>
> " in inlist_zams, &controls.
> The following two pictures are results of 0.085 and 0.2 M_sun.
> --------------------------------------------------M = 0.085
> M_sun-----------------------------------------------------------
>
> -------------------------------------------------M = 0.2
> M_sun--------------------------------------------------------------
>
> Their trajectories on HRD are much different from Fig. 15 in paper Modules
> for Experiments in Stellar Astrophysics (MESA) 2010. This firgure is
> displayed following
>
> We can see that:
> 1) The shape of the trajectory is not quite the same as the trajectory on
> the paper.
> 2) The ending of the evolution is different. For example, the ending of
> the 0.2 M_sun trajectory in my results, Log Teff=3.55, the ending of the
> 0.2 M_sun in paper's results, Log Teff < 3.525.
> The calculation is so different. After reading paper, I realized that
> maybe I hadn't considered deuterium and lithium burning, so I checked out
> the output file and found that deuterium and lithium had been zero
> throughout the evolution. So how do I set the initial elements in mesa?
> Because it seems like I can only set the abundances of H, He, and metals,
> but not the abundances of deuterium, the isotope of H.
> Faced with the above problems, I hope to get your help. Would you please
> offer me some advice on? Thanks you a lot.
>
> Thanks!
> LiJiaxun
> _______________________________________________
> mesa-users at lists.mesastar.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users
>
>

-- 

Dr Meridith Joyce
Marie Sklodowska-Curie Actions Widening Fellow
CSFK Konkoly Observatory, Budapest, Hungary 1121
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