[Mesa-users] Question about tidal synchronization and circulization

[Pablo Marchant]

Thanks Ali,

looking into your inlists I see two things:

- you do not specify eccentricity. This means the system will be
initialized with zero eccentricity so tidal circularisation is not expected
to do anything to the model.
- to model tidal synchronization, you need to include stellar rotation. In
the star_job section of inlist1 (and inlist2 when you model both stars) you
need to include (details here
https://docs.mesastar.org/en/release-r21.12.1/reference/star_job.html#new-rotation-flag
):

new_rotation_flag = .true.change_initial_rotation_flag = .true.

Let me know how that works.

Cheers!

On Wed, Jan 26, 2022 at 7:53 PM Ali Pourmand <pourmand at ualberta.ca> wrote:

> 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
>>
>

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