[Mesa-users] Issue with rotation in MESA r22.11.1

[Torres, Guillermo]

Hi Matteo,

Thanks for the quick reply.

On Thu, Jan 23, 2025 at 3:09 PM Matteo Cantiello <matteo.cantiello at gmail.com>
wrote:

> Hi Willie,
>
> It seems like you’re suggesting that the shape of the evolutionary track
> is ‘odd,’ but I think it’s more accurate to say that it differs from the
> PARSEC model. This difference isn’t entirely surprising, as the MESA
> calculation reaches critical rotation, while the PARSEC model does not.
>

Yes, I certainly agree with that.

There could be a variety of factors contributing to the discrepancy -- such
> as differences in initial conditions, the treatment of mixing, or angular
> momentum transport -- and it’s difficult to pinpoint the exact cause based
> solely on the inlist and plot you’ve provided.
>
> If the goal is to reproduce the PARSEC results, you’ll want to ensure the
> physics and initial conditions in your MESA setup match those in the PARSEC
> calculation as closely as possible. Once that alignment is achieved, if
> differences still persist, it would be ideal to run both PARSEC and MESA
> side by side and compare results throughout the evolutionary stages. This
> approach might help identify where the divergence arises.
>

My goal is not really to reproduce the PARSEC results exactly or
quantitatively (e.g., in terms of luminosity or temperature), as there are
probably so many differences in the physics of the two codes that it would
be unlikely one could do that. Instead, I was simply struck by the
morphology of the blue hook in MESA, which is so different from the
'familiar' shape seen with PARSEC, as well as the few other models for
rotating stars that I have seen in the literature.

Ideally one would want to run PARSEC and MESA in parallel, as you suggest,
though this is more easily said than done, and would obviously require
access to the PARSEC code. In any case, from feedback from others, it
appears I'm not the first to encounter this problem, and it would seem
prudent to ignore the part of the tracks that come so close to breakup.

Willie


>
> --
> Matteo Cantiello - https://www.stellarphysics.org/
> Research Scientist,  CCA, Flatiron Institute
> Visiting Associate Researcher, Princeton University
>
>
> On Thu, Jan 23, 2025 at 2:53 PM Torres, Guillermo via Mesa-users <
> mesa-users at lists.mesastar.org> wrote:
>
>> All,
>>
>> I am using MESA r22.11.1 to model the evolution of a rapidly rotating
>> star of 5.04 solar masses (initial w/w_crit = 0.55), and I'm finding an odd
>> shape for the evolutionary track in the blue hook region, as the star is
>> contracting. During this phase, I see the model reaching very high values
>> of w/w_crit up to the limit of 0.99, and as it approaches that value, the
>> morphology goes haywire, at least compared to a similar track from the
>> PARSEC v2.0 series (see figure attached, with the odd part highlighted in
>> red). I'm wondering if this really is an issue with the physics in MESA, or
>> just that I don't have the right controls in my inlist. It appears the star
>> would need to get rid of more of its angular momentum to avoid this, but
>> evidently it is not doing that with the controls I am using. I attach my
>> inlist for reference. The pre-main-sequence part is computed separately. I
>> would be thankful for any suggestions.
>>
>> Willie
>> _______________________________________________
>> mesa-users at lists.mesastar.org
>> https://lists.mesastar.org/mailman/listinfo/mesa-users
>>
>>
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