[mesa-users] Jumps in temperature during evolution of helium stars

[Aaron Dotter]

Hi Pablo,

I am suspicious of the EOS, particularly the blend between OPAL and SCVH.
Can you make some T-rho profile plots and compare with the ever-popular
figure 1 from MESA paper I?  Another way to check this would be to switch
to only HELM, which can be done in controls.defaults.

Aaron

On Sat, Dec 12, 2015 at 4:48 AM, Pablo Marchant <pamarca at gmail.com> wrote:

> Hello mesa-users!
>
> For the last weeks I've been working on models of helium stars formed by
> chemically homogeneous evolution product of efficient rotational mixing.
> I've consistently run into an issue though, midway through helium burning
> my models experience sudden jumps in temperature. Here I attach an example
> of a 67 msun star with a metallicity of Z=0.00034 settling into the helium
> ZAMS, for simplicity I removed rotation and any associated mixing effects.
> When core helium drops to about 0.60, the outer layers experience a sudden
> change in a few timesteps which I can't seem to resolve (see figure
> prof.pdf, note that the saved model starts at model 1500). There is not
> really to my knowledge any fundamental change that could cause a sudden
> jump in this stage of evolution.
>
> I know this star evolves towards the Eddington limit, so I also tried
> applying MLT++, but it does not make much of a difference, as depicted in
> the attached HR diagram.
>
> Anyone has ran into similar issues while modeling helium stars? Any clue
> what might be amiss here?
>
> FYI, i'm using r7624
>
> Cheers!
>
> --
> Pablo Marchant Campos
> M.Sc on Astrophysics, Universidad Católica de Chile
> PhD student, Argelander-Institut für Astronomie
>
>
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