[Mesa-users] Questions about (step)Overshooting

[Nathan Grin]

Hi Matheus,

Indeed, for step overshooting, f0 is just a trick
my guess is that the differences you see are due to applying exponential on
the h/he shells during post-core-H phases, for exp overshooting f0 does
make a difference

what i don't understand is:
in the current inlists, you are applying step overshooting to the h/he
shells, not exponential (but i guess you change em for each run?), do you
also see differences when only applying step?
are you changing all the f0s simultaneously? i.e. f0_above_burn_h_core ==
f0_above_burn_h_shell ==  f0_above_burn_he_core == f0_above_burn_he_shell

hope this helps,
cheers,
nathan


On Fri, 28 Sep 2018 at 01:40, Matheus Bernini via Mesa-users <
mesa-users at lists.mesastar.org> wrote:

> Hello,
>
> I'm an undergraduate student and I'm studying evolution of massive stars
> using MESA.
>
> I was "playing around" with step overshooting initial values (
> overshoot_f0_...) for hydrogen helium and nonburn core/shell and I noticed
> that slightly changes on f0 (but always keeping f - f0 = 0.1) caused great
> changes on the post-MS phases [figure].
>
>
>     overshoot_f0_above_burn_h_core = 0.035
>     step_overshoot_f_above_burn_h_core = 0.135
>
> vs.
>
>     overshoot_f0_above_burn_h_core = 0.030
>     step_overshoot_f_above_burn_h_core = 0.130
>
> *For completeness, there was also an exponential overshooting on all of
> the models of 0.001 on helium and hydrogen core/shell
>
> If I understood correctly, the f0 is the starting point for the overshoot
> inward the region (core or shell) because the mixing coefficient is 0 on
> the edge of the region, not allowing the computations to happen. So, if f0
> is just a "trick" to allow the computation of the overshoot, why changing
> it a little causes important changes on the evolution?
>
> Thanks :)
>
> -----------------------------------------------------------------
> *Matheus Bernini Peron*
>
>
> * Undergraduate student Observatório do Valongo,Universidade Federal do
> Rio de Janeiro*
>
>
>
> *Ladeira do Pedro Antônio, 43 - SaúdeRio de Janeiro - RJ - CEP
> 20080-090Brasil*
> ___________________________________________________________
> Evolution 32Msun, no rotation, Z_init = 0.014, Y_init = 0.266
> red: 0.135 - 0.035
> blue: 0.130 - 0.030
> gray: GENEC (Ekstrom+2012)
> [image: image.png]
> _______________________________________________
> mesa-users at lists.mesastar.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users
>
>
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