[Mesa-users] Radius of a planet

[Josiah Schwab]

Hi Claudio,

Please continue to CC mesa-users so that our messages will be archived
and can be searched by future users.

>> The radius reported by MESA will be the radius of the surface cell
>> (i.e. the location where your outer boundary condition is applied.)
>>
>> If you would like to compute and report a different radius using the
>> properties of the model, you can do so during the calculation using
>> run_star_extras.
>>
>
> I know that the radius is the location where the boundary condition is
> applied, but how to change this location?
>
> I am already using run_star_extras to implement an accretion of gas
> and solids varying with time, what subroutine should I modify or add
> to compute a different radius (or changing the location where the
> outer boundary condition is applied)?

That's not really a meaningful question for a Lagrangian stellar
structure code like MESA.  You don't get to change or choose the radius.

You may find it helpful to look through Section 6.2 of Paxton et
al. (2011) which describes the equations that are being solved.

The outer boundary conditions are T and P at the surface and you are
already specifying both those.  The radius of the outer zone will then
come from satisfying the rest of the equations.

Hope that helps,
Josiah