[Mesa-users] eps_grav is always 0

[Huaiyu Duan]

Thank you all for the information! This makes sense.

— Huaiyu (Mike)
Sent from my phone

On Aug 16, 2025, at 10:03 AM, Jared Goldberg <jgoldberg at flatironinstitute.org> wrote:


  [EXTERNAL]
Just to be explicit: This is a bug which should be fixed in an upcoming release. Eps_grav is calculated and used in the code, but not output properly. You will need to use run_star_extras as Zhao and Susmita describe to report the quantity in the current public release.

Cheers,
~Jared

On Aug 16, 2025, at 7:38 AM, Susmita Das via Mesa-users <mesa-users at lists.mesastar.org> wrote:


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<mailto: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<mailto: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<mailto: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)
>
> _______________________________________________
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>
>
>
> --
> Zhao Guo
> www.astro.gsu.edu/~guo<http://www.astro.gsu.edu/~guo>

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