[Mesa-users] adding some extra energy to the Sun

[Matteo Cantiello]

Hi Pau,

MESA provides a way to override most of the physics routines with no need
to modify anything more than run_star_extras. You can add energy to the
stellar structure using the other_energy routine
https://docs.mesastar.org/en/latest/using_mesa/extending_mesa.html#
See an example of this from the MESA 2021 summer school:
https://jschwab.github.io/mesa-2021/solutions.html#org417d2fb
Many other useful examples / exercises here:
https://cococubed.com/mesa_market/education.html

On a related note, It is unclear to me why the star should pulsate after
injecting the energy. My expectation is that the extra energy would be lost
on the relevant thermal timescale. So the star would expand initially and
then relax back after the energy injection, reaching thermal equilibrium.
If you inject a lot of energy, quickly, and close to the surface, the star
might experience a dynamical event (eg mass loss). That might be tricky to
simulate. But again I would not expect sustained pulsations *unless* the
star is temporarily driven in some instability strip.

Cheers,

Matteo

--
Matteo Cantiello - https://www.stellarphysics.org/
Research Scientist,  CCA, Flatiron Institute
Visiting Associate Researcher, Princeton University

Sent via Superhuman <https://sprh.mn/?vip=matteo.cantiello@gmail.com>


On Mon, Oct 03, 2022 at 11:38 AM, Mare Dedeu <mesa-users at lists.mesastar.org>
wrote:

> Dear all,
>
> I would like to create a model for a Sun-like star, give it an input of
> energy corresponding to about 1e-3% its binding energy and then let it
> evolve.
> I.e. like we compress the Sun and then let it go. It will start pulsating
> (think of it as e.g. the impact of the Moon on the surface of the Sun,
> depositing an amount of energy X).
>
> I am interested in the evolution of the star in the HR diagram but also in
> the pulsations via the kappa (or maybe epsilon mechanism) that it will
> experiment.
>
> I have installed MESA and gyre, but I am unsure on how to create the
> initial conditions for MESA. I think it should be rather simple to add that
> extra energy.
>
> I would appreciate it a lot if somebody could walk me through this or, at
> least, give me a few hints on how to do it.
>
> Later, to analyse the pulsations, I have seen that gyre can directly read
> a mesa file, so that I am guessing that this is what I need.
>
> As I said, ideally a detailed explanation would be perfect but any input
> would be very much appreciated.
>
> Thanks a lot!
>
> Pau
>
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>
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