[mesa-users] element diffusion on the white dwarf cooling process

[Mike Montgomery]

Hi Chen,

> Dear mesa-users:
> 
> I am Chen Yanhui, coming from YunNan astronomical observatory-Chinese academy of science. Mesa version of 4298 is installed on my computer and 1M_pre_ms_to_wd is used. With wd_cool, the white dwarf model is cooled down. In the cooling process, I want to take the element diffusion into account.
> 
> do_element_diffusion = .true.
> 
> diffusion_dt_limit =3.15d7
> 
> I find that the evolution timestep is always lower than 'diffusion_dt_limit ' and acturely there is no diffusion. How can I take the element diffusion into account? There is no or little convection on the surface, but the profiles show about 70% hydrogen and about 30% helium. The element diffusion can make them more divided. Thank you very much.

This is easy to do. Just set 

diffusion_dt_limit = 1d3

and you will see diffusion starting to happen for the white dwarf case. So, in order for diffusion to occur, diffusion_dt_limit needs to be smaller than the evolution time step.

Cheers,

Mike
_____________________________________

Michael Houston Montgomery
Department of Astronomy
University of Texas
email:  mikemon at astro.as.utexas.edu
http://rocky.as.utexas.edu/~mikemon/
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