[Mesa-users] eps_grav is always 0

[Huaiyu Duan]

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