[Mesa-users] Creating a Highly Irradiated Super-Earth

[amber lauer]

1D-7 seems high for a minimum timestep. Where do you see that is
"recommended"? When working with a new model where you have difficulties
with stability, it often helps to loosen the computational constraints
until you get a stable version. Minimum timestep is one of the first ones I
change.
=================================
Dr. Amber Lauer
Postdoctoral Researcher
Triangle Universities Nuclear Lab
Duke University
amber.lauer at tunl.duke.edu <amber.lauer at duke.edu>


On Fri, Jan 24, 2020 at 2:53 PM Brian Jackson <bjackson at boisestate.edu>
wrote:

> I've conducted additional experiments, and I think I'm starting to see
> what the issues might be.
>
> I've attached inlists and a model for a slightly different approach.
> The model calculation behaves fine until about 4 Gyrs out, when the
> timestep suddenly plunges and the code fails to complete the run. For
> some reason, the central degeneracy parameter goes haywire shortly
> before the run ends -- see attached History_Plot.png.
>
> Looking at the 2011 MESA instrument
> (
> https://urldefense.proofpoint.com/v2/url?u=https-3A__ui.adsabs.harvard.edu_abs_2011ApJS..192....3P_abstract&d=DwIBaQ&c=imBPVzF25OnBgGmVOlcsiEgHoG1i6YHLR0Sj_gZ4adc&r=IZ3U2LUL6yhDK-Uf8F_eU9W85o61MM43boq-nVwHt38&m=VUMjn3TtPcQDhrIdYRUN4iHF2HTgi2wOtFYjHuaOou4&s=wpqHgLeePFLJvg_YLSXwPgXc1RkPvMS8vkgozvkrNbU&e=
> ), it
> seems the model core may be nearing a transition in the equation of
> state (log(density) = -0.19, log(temp) = 3.79 -- see attached Figure
> 1). Is there a reason why that transition would severely and abruptly
> modify the degeneracy parameter? Is there a way to smooth this
> evolutionary phase?
>
> Or have I completely misunderstood what's going on?
>
> Thanks,
> Brian
>
> On Wed, Jan 22, 2020 at 5:58 PM Brian Jackson <bjackson at boisestate.edu>
> wrote:
> >
> > Dear MESA Users,
> > I am still struggling to create highly-irradiated super-Earths using
> MESA.
> >
> > I have attached the inlists and saved models I'm using to create a
> > 20-Earth mass planet with an envelope mass fraction of 20% (i.e., a
> > core mass of 16 Earth masses) and an irradiation 20 times Earth's
> > (i.e., 2.72e7 ergs/s/cm^2).
> >
> > I attempt to create the planet by irradiating a gas giant planet and
> > then relaxing the mass down to my desired mass. (I've found doing it
> > the other way around leads to badness.) I've tried tweaking lots of
> > settings, but nothing seems to work. In the end, I wind up with a
> > timestep below the suggested minimum of 9.9999999999999995D-07.
> >
> > I am using Mac OS 10.13.1, MESA 11701, and the most recent version of
> > the SDK (August 30 2019).
> >
> > Please forgive me if I forgot any required information.
> >
> > Thanks,
> > Brian
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