[Mesa-users] Question about tidal synchronization and circulization

[Ali Pourmand]

Hi Pablo,

Sorry for not including any details. It's nothing complicated, just a
binary system, in which only one star evolves.
I am trying to evolve it, with a threshold for the maximum radius the star
could reach. I am trying to do it once by including the tidal
synchronization, and once without it.
I have attached the inlists I use below. Inlist 1 and 2 are the same for
both cases; but the inlist_project is different for the two cases where I
have switched tidal_sync on in one of them, and off in the other.


What has made me curious is that the orbital separation (and all other
properties) goes through the same evolution both with and without the tidal
sync switch module being on or off. For example, for a 3Msun donor with a
1.875Msun companion and 9.47Rsun initial separation, the plots of angular
momentum, and photospheric radius and orbital separation as a function of
age looks like the plots below, with both inlist_project_with_tides, and
inlist_project_no_tides.

Am I writing something wrong in my inlists that switching tidal
synchronization on and off makes no difference? (I had the same problem
with the
   "do_tidal_circ=.false." command, switching it from true to false doesn't
have any effect on the outcome)
[image: Js_vs_age.png]
[image: radiusvsage.png]
Best,
Ali

On Wed, Jan 26, 2022 at 10:49 AM Pablo Marchant <pamarca at gmail.com> wrote:

> Hi Ali,
>
> it would be useful if you share your full inlists to understand your
> problem (both inlist_project as well as the individual inlists of each
> star). It's also useful if you provide a description of what type of system
> you're actually trying to model.
>
> Cheers
>
> On Wed, Jan 26, 2022 at 1:26 AM Ali Pourmand <pourmand at ualberta.ca> wrote:
>
>> Hello,
>>
>> I have been having a problem with the MESA binary package, namely on the
>> tidal synchronization and circulization switches; I can't seem to turn
>> these effects on or off.
>>
>> I have evolved my stars with two different inlists; the first one has:
>>
>>    do_tidal_sync = .true.
>>
>>    sync_type_1 = 'Hut_conv'
>>    sync_type_2 = 'None'
>>    sync_mode_1 = 'Uniform'
>>    sync_mode_2 = 'Uniform'
>>    do_initial_orbit_sync_1 = .true.
>> -----------------------------------------
>> The second one has:
>>
>>    do_tidal_sync = .false.
>>
>>    do_initial_orbit_sync_1 = .false.
>> ---------------------------------
>> I also tried evolved with both true and false for the following switch:
>>    do_tidal_circ = .true.
>> ------------------------------------
>>
>> None of these make a difference in the outcomes whatsoever.
>> I wanted to ask whether I am not including something in the inlists, or
>> is there another problem.
>>
>> More generally, Is the code's default to initiate tidal synchronization
>> or not? I am also wondering how there are two independent switches for
>> circulization and synchronization; namely, is it possible for one switch to
>> be off without the other?
>>
>> Best
>> Ali Pourmand
>> M.Sc. student,
>> University of Alberta
>>
>> _______________________________________________
>> mesa-users at lists.mesastar.org
>> https://lists.mesastar.org/mailman/listinfo/mesa-users
>>
>>
>
> --
> Pablo Marchant Campos
> M.Sc on Astrophysics, Universidad Católica de Chile
> PhD on Astrophysics, Argelander-Institut für Astronomie, Universität Bonn
>
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