[Mesa-users] Using make_o_ne_wd for a helium star

[Evan Bauer]

Hi Charlie,

Interesting idea! What was the initial mass of the model for the plots that you sent? With the much higher helium content in your models, I believe they will end up producing much larger C/O cores for a given initial mass. Past a certain point (and certainly for masses as large as 10 Msun), this will mean that they will proceed to more advanced stages of burning rather than ending as an O/Ne WD. The plots that you sent show that this particular model has C/O/Ne layers that extend well beyond the Chandrasekhar mass, and in fact the core is already advancing into later burning stages, so this model should end its life as some sort of core collapse supernova rather than a WD.

If you want to continue following the evolution and see where this model ends up, you might find it instructive to look at some examples of more massive stars, like make_pre_ccsn_IIp.

Cheers,
Evan

> On Aug 5, 2021, at 8:59 PM, Charlie Sharpe via Mesa-users <mesa-users at lists.mesastar.org> wrote:
> 
> Hello MESA users,
> 
> I am trying to use the make_o_ne_wd test suite to model the entire life cycle (birth to WD) of high mass stars (up to 10 solar masses, or more if possible) of helium stars. This test case seems to be able to achieve this assuming standard initial elemental abundances of 28% helium, 70% hydrogen, etc. However, I am trying to model a star with a very high initial helium abundance (75%+) with low metallicity. When I change the initial composition to this, the model seems to reach to carbon burning before the time step drops below 10^-6 seconds and the code is cut off. Terminal seems to say that the dt_limit for the models before it crashes are either 'retry' or 'hold' (or 'max increase' of course), so I am not sure how to gain any idea as to what would need to be changed here.
> 
>  Any suggestions about what the process would be to resolve this?
> 
> I have attached the Trho_profile plot as well as the abundance plot at the point where the time step causes the code to be cut out. I would attach the inlists but they're basically identical to the ones in the make_o_ne_wd test suite but with initial_y = 0.75 and initial_z = 0.000001.
> 
> Thanks in advance,
> 
> Charlie
> 
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