[Mesa-users] Stationary model

[g.mirouh at surrey.ac.uk]

Hello everyone,

On 13/11/2018 06:04, Pablo Marchant wrote:
> Hi,
>
> depending on what exactly you're trying to do your message could be 
> interpreted in different ways. Something that might be close to what 
> you're looking, is to fix the composition of the star by setting
>
> dxdt_nuc_factor = 0d0
> mix_factor = 0d0
>
> the first option will keep the energy input from nuclear reactions, 
> while ignoring the corresponding changes in composition. The second 
> one will remove composition changes due to mixing. You don't want to 
> turn off nuclear reactions, because if you do that the star will 
> simply lose energy and evolve to higher central temperatures in a 
> Kelvin-Helmholtz timescale. If you use these option, you will freeze 
> the evolution of the star if you are dealing with phases in thermal 
> equilibrium. If the starting model is not in thermal equilibrium, then 
> it's trickier.

Thank you Pablo. I implemented these two commands in my inlist, but my 
model is not fixed: when I force the dx/dt to 0, the core brutally 
expands to find some material to burn... and that's not my aim here.

What I want is simply to completely freeze my model at a given 
composition and have it not change anymore. So yes, as you said, I 
literally want to fix the structure variables in the star. I guess it 
sounds simpler than it is actually...

Thanks a lot to anyone who can help.

-- 
Gio.