[Mesa-users] Question regarding do_tidal_sync

[Pablo Marchant]

Hi Bear,

Without more information it is unclear if the difference on the fifth digit
you mention is incorrect. What kind of system are you modeling precisely
(always better to share inlists and other input files)? What were you
expecting from the model and why? Does the star evolve towards
synchronicity?

there are two controls taking care of activating tides in MESA:

- do_tidal_sync, this is by defalt set to false. It determines whether
there is a torque term applied to each star.
- do_jdot_ls, which defaults to true. This determines if there is a sink
term in the equation for the evolution of orbital angular momentum which
accounts for the torque imparted on the stars.

One important thing is that these controls assume you have rotation
included in your stellar models. do_jdot_ls only accounts for the torque
applied through the star, and do_tidal_sync can only apply a torque if
there is rotation included in the star. But you should beware of how tidal
strength is actually computed (see various options in the documentation).
I'd suggest you take a closer look at these as well.

Cheers

On Tue, Oct 26, 2021 at 8:08 AM Bear Ealeal via Mesa-users <
mesa-users at lists.mesastar.org> wrote:

> Dear MESA users,
>
> I am trying to run MESA binary+point mass, where the star is a MS and the
> point mass is a planet.
>
> I turned on do_tidal_sync = .true.
> I did it for both MESA 10398 and MESA 15140.
> I am not sure what "do_tidal_sync"  does, if it is true or false, tidal
> occurs and I see that the  binary separation decreases.
>
> In the defaults it says:
>
> ! If true, apply tidal torque to the star
>       do_tidal_sync = .false.
> But true or false, I get the same results up to the 5 digit...
>
> Do  you know what it does and on which parameter it effects?
>
> Thank you very much for you help,
>
> Ealeal
>
>
>
> _______________________________________________
> mesa-users at lists.mesastar.org
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>
>

-- 
Pablo Marchant Campos
M.Sc on Astrophysics, Universidad Católica de Chile
PhD on Astrophysics, Argelander-Institut für Astronomie, Universität Bonn
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