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

[Mark Eberlein]

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