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

Mare Dedeu lamarededeusenyor at googlemail.com
Mon Oct 3 17:08:24 UTC 2022

Hi Matteo,

thanks a lot for pointing me to those! Yes, you are right. In principle the
energy should dissipate in a thyd, which is of about 30 min in the case of
the Sun. Maybe I posed the question in a wrong way. I am expecting the
nonadiabaticity and lack of sphericity to play a role in the vibrational
unstability. But I am not sure, which is why I want to start looking at
this scenario and then make it gradually more complex.

I might have more questions in the future. Thanks a lot.

Missatge de Matteo Cantiello <matteo.cantiello at gmail.com> del dia dl., 3
d’oct. 2022 a les 18:23:

> 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
>> _______________________________________________
>> mesa-users at lists.mesastar.org
>> https://lists.mesastar.org/mailman/listinfo/mesa-users
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