[Mesa-users] eps_grav is always 0

[Susmita Das]

Dear Huaiyu,
Adding “ energy_eqn_option = ‘eps_grav’ ”  to `inlist_project` is indeed
correct.
In addition, adding a new profile column using s% eps_grav_ad(k)% val in
run star extras should do the job.
https://github.com/MESAHub/mesa/blob/main/star/private/profile_getval.f90#L1201

Please let us know if this works. If not, I'll give it a try (please send
your inlists and run star extras file).

Best,
Susmita

On Sat, Aug 16, 2025 at 1:39 AM Huaiyu Duan via Mesa-users <
mesa-users at lists.mesastar.org> wrote:

> Hi Zhao,
>
> Thanks for your response! I didn’t attend the summer school.
>
> By reading through the page, it seems that I need to add line “
> energy_eqn_option = ‘eps_grav’ ”  to `inlist_project`. But `eps_grav` is
> still 0 in the profile files after I do that.
>
> I understand that can add `ez_eps_grav` to the history files for the value
> of `eps_grav` at the base of the convection zone. For that purpose, one
> needs to modify `run_star_extras.f90` and recompile because this variable
> is user defined. But I don’t think I need to do that.
>
> Any suggestion? I’m using mesa-24.08.1.
>
> — Huaiyu (Mike)
>
> > On Aug 15, 2025, at 9:44 AM, Zhao Guo <fffeynman at gmail.com> wrote:
> >
> >   [EXTERNAL]
> > Dear Huaiyu,
> >
> > This issue was addressed in a lab developed by Susmita Das for the MESA
> Summer School 2025; see
> https://mesa-leuven.4d-star.org/tutorials/thursday/lab-1/ for details.
> >
> > Best,
> > Zhao
> >
> > Huaiyu Duan via Mesa-users <mesa-users at lists.mesastar.org>
> 于2025年8月15日周五 13:28写道：
> > Hello,
> >
> > Sorry for asking a probably simple question. I ran the latest MESA code
> to evolve a 30 Msun model to ZAMS. I copied “profile_columns.list” from the
> default and uncommented line "eps_grav ! -T*ds/dt (negative for
> expansion)”. To my surprise, its values are exactly 0 even for the first
> profile. Is this expected?
> >
> > — Huaiyu (Mike)
> >
> > _______________________________________________
> > mesa-users at lists.mesastar.org
> > https://lists.mesastar.org/mailman/listinfo/mesa-users
> >
> >
> >
> > --
> > Zhao Guo
> > www.astro.gsu.edu/~guo
>
> _______________________________________________
> mesa-users at lists.mesastar.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users
>
>

-- 
Dr. Susmita Das
Post-doctoral Fellow, IUCAA Pune, India
co-Chair, IAU EC Working Group of Junior Members
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