[Mesa-users] Producing a medium to high mass pure Helium star

[Aaron Dotter]

Hi Charlie,

How far do you want these He stars to evolve?

The model shown in your plot is quite evolved, having two shell burning
regions, one carbon-burning and one helium-burning, a degenerate core of
more than 0.5 Msun.

The evolved state of this model is likely to explain the small timesteps.
Based on what information you provided, it's possible that the reason why
the results change around 0.8 Msun is that models more massive than this
are able to enter into carbon burning and those less massive are not.

Aaron

On Wed, May 19, 2021 at 7:07 AM Charlie Sharpe via Mesa-users <
mesa-users at lists.mesastar.org> wrote:

> Hello,
>
> I am currently trying to simulate a pure Helium star. Everything seems to
> run smoothly for masses below 0.8 M_solar in the sense that the code
> doesn't freeze out (see below). However, as soon as I set a mass above 0.8
> M_solar, such as 1 M_solar shown here, the time steps become smaller and
> smaller and the code freezes out. I let it run for 42000 models, where in
> the first 4000 models it progressed about 1.5e7 years, but in the last
> 38000 models it only progressed a further 2.5e4 years with no indication of
> any significant further progress.
>
> I have attached a screenshot of the T - rho profile from one of the models
> towards the end of the run in case you were curious as to what stage it
> freezes at.
>
> I have also attached my inlist. Any help as to why this would be
> occurring and/or how to fix it would be absolutely awesome.
>
> Kind regards,
> Charlie
> [image: Screen Shot 2021-05-19 at 8.52.27 pm.png]
> _______________________________________________
> mesa-users at lists.mesastar.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20210519/b19d40ee/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Screen Shot 2021-05-19 at 8.52.27 pm.png
Type: image/png
Size: 328283 bytes
Desc: not available
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20210519/b19d40ee/attachment.png>