[mesa-users] MESA for giant planet initial thermal evolution

[Ana-Maria Piso]

On Wed, Apr 23, 2014 at 1:28 PM, Bill Paxton <paxton at kitp.ucsb.edu> wrote:

>
> On Apr 23, 2014, at 7:02 AM, Ana-Maria Piso wrote:
>
> Hi,
>
> I am new to MESA, so I apologize if this question has already been
> answered somewhere else. I would like to use MESA to model the evolution of
> a giant planet embedded in a gas disk -- the standard core accretion
> calculation, assuming that the core has a fixed mass. The 'make_planets'
> test case is probably a good place to start, but I need to:
>
> (a) fix the outer boundary conditions to constant T and P, which I haven't
> seen as an option in the standard MESA controls
>
>
> mesa has lots of fancy outer boundary conditions, but it is missing the
> simple case of fixed T and P --- I can show you how to do it yourself if
> you're willing to plunge into using run_star_extras and writing a small
> routine to replace the standard atm package.   let me know if you'd like to
> try that.
>

Sure, I would like to try that since it seems like the cleanest option.
I've used python a lot, but not C, so if you could show me how to write
this subroutine in run_star_extras, that'd be great.



>
> alternatively, have you considered using this:
> which_atm_option = 'grey_irradiated'
>             ! based on Guillot, T, and Havel, M., A&A 527, A20 (2011).
>
> see the "irradiated_planet" test case in star/test_suite.
>
>
> (b) include a variable mass accretion rate M_dot = (M_i+1 - M_i) / dt,
> where i is the current model.
>
>
> the simplest way to start is to set a constant rate in your inlist ---
> seach for "mass gain or loss" in star/defaults/controls.defaults
>

That sounds like a good start! However, since the mass accretion rate is
not going to stay constant throughout the evolution, is there a simple way
to vary Mdot while evolving the planet based on previous steps?

Thanks,
Ana


>
>       mass_change = 0d0 ! rate of accretion (Msun/year).  negative for
> mass loss.
>          ! this only applies when the wind scheme = ''
>
>
> -Bill
>
>
>
>
>
> I'm not sure how to do this / where to start, so any help would be greatly
> appreciated.
>
> Best,
> Ana
>
> --
> Ana-Maria Piso
> Graduate Student
> Harvard University Department of Astronomy
> apiso at cfa.harvard.edu
>
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-- 
Ana-Maria Piso
Graduate Student
Harvard University Department of Astronomy
apiso at cfa.harvard.edu
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