[Mesa-users] Thermal Relaxation from Relaxing composition, entropy, angular momentum

[Francis Timmes]

> Perhaps to write to the history file during the entropy relaxation?

i recall this was a capability at one point, but got dropped.

maybe 

https://docs.mesastar.org/en/release-r23.05.1/reference/star_job.html#disable-pgstar-during-relax-flag

disable_pgstar_during_relax_flag = .false.

will be useful to at least watch the model during a relaxation process.

fxt






> On Jun 29, 2023, at 12:48 PM, Charles Gibson via Mesa-users <mesa-users at lists.mesastar.org> wrote:
> 
> Hello,
> 
> I recently was able to figure out how to evolve a star from composition, entropy, and angular momentum profiles as described in star_job (composition, entropy, angular momentum) with help from the users on this list. The model that I am looking at is a stellar collision remnant from using SPH, and I am expecting it to be puffed up and more luminous at the very beginning of the evolution. However, when I relax the star in MESA and observe its evolution, the star doesn't demonstrate this thermal relaxation. I have decreased the timescales for these relaxation variables to the smallest that MESA can handle for the particular model (leading to the star's first model being ~100 years old).
> 
> Here is a figure that shows the expected track from a post-collision star (from this paper by Sills, et. al). The "C" marks the point in the collision where the merger product was pulled from the SPH and inputted into this separate evolution code. After the collision, the product quickly decreases in luminosity as thermal equilibrium is reached.<Blue Straggler Paper Fig 7.png>
> 
> When running my MESA runs, I am getting something closer to the figure below. The star doesn't begin at a more luminous position. Instead, it begins on a point close to its expected later evolution:<Mixing vs no Mixing.png>
> 
> Is there an inlist setting that I am missing? Perhaps to write to the history file during the entropy relaxation?
> 
> Thanks,
> Charlie
> 
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