[Mesa-users] Very low density and temperature regime: Initial model for clump evolution

[Frank Timmes]

hi mark,

posting a minimal working example can be useful should someone want to look.

fxt



> On Dec 7, 2023, at 6:37 AM, Mark Eberlein via Mesa-users <mesa-users at lists.mesastar.org> wrote:
> 
> Dear MESA users,
> 
> I'm a PhD student who recently started working with MESA (r23.05.1) to study planet formation. Therefore I would like to simulate a very low density and low temperature clump mostly of H and He that cools down and eventually collapses rapidly. The initial mass should be around 10 MJup stretching over ~2.8 AU. In Helled and Bodenheimer 2010, they found a solution to the hydrostatic equations with an initial central temperature of ~500K and a density of ~7e-10 g/cm2.
> 
> I'm having troubles creating even an initial model. I have tried both the create_initial_model method as well as relaxing the mass of a pre-main sequence star but both lead to errors presumably because the temperature gets too low. For the create_initial_model I get an error saying "failure in eosPT_get_T", which is confusing me. As far as I understood the documentation and the code the eos falls back onto ideal gas which should be well defined for the temperatures I encounter.
> To make sure the ideal gas eos is called I created an other_eos hook that calls the ideal gas routine (get_ideal_for_eosdt in the ideal module of eos) for the entire regime of the T-rho space and still I get the same error.  I assume there is something else going on I don't understand maybe in the way mesa tries to find an initial model.
> 
> Any suggestion or comment is highly appreciated or even some experience with low T and rho regimes.
> 
> Many thanks and kind regards,
> Mark
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