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

[Bill Paxton]

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.

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

      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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