[Mesa-users] Turn off binary interactions

[Mathieu Renzo]

HI Levi,

If it is for an exploratory run, I would also go the route suggested by 
Bill. If you are running grids and don't want to stop and restart many 
runs, you could catch the condition m1=m2 in the run_binary_extras.f 
(e.g., in the  binary_extra_finish_step routine) and from there modify 
on the fly a few inlist parameters.

I think you want ignore_rlof_flag = .true. (not false), but that may not 
be sufficient to turn off all forms of interactions. I would also set 
the variables below to turn off tides and other angular momentum-related 
binary options:

    b% do_tidal_sync = .false.
    b% do_j_accretion = .false.
    b% do_jdot_mb = .false.
    b% do_jdot_missing_wind = .false.
    b% ignore_rlof_flag = .true.

You can even change the period and eccentricity at that point using 
binary_set_separation_eccentricity defined in binary_lib. At the link 
below, you can find an example where I do these things (and some more 
you don't want, like turning the donor into a point-mass):

https://github.com/MESAHub/mesa-contrib/tree/release/hooks/detach_binary

Hope this helps,
Mathieu

On 9/15/23 10:06, Wolf, William M via Mesa-users wrote:
>
> Hi Levi,
>
> Could you just stop the run when their masses are equal, save the 
> models, and then run independent simulations in star? It seems you no 
> longer have need of the binary module beyond that point.
>
> Regards,
>
> Bill Wolf
>
> *From: *Mesa-users <mesa-users-bounces at lists.mesastar.org> on behalf 
> of Levi via Mesa-users <mesa-users at lists.mesastar.org>
> *Date: *Thursday, September 14, 2023 at 11:59 PM
> *To: *mesa-users at lists.mesastar.org <mesa-users at lists.mesastar.org>
> *Subject: *[Mesa-users] Turn off binary interactions
>
> Hi all,
>
>  I am writing to seek assistance with aspects related to the double_BH 
> module in the MESA. I want the model to halt any binary interactions 
> when m1 and m2 have equal mass and allow them to evolve as two 
> independently stars. Initially, I set b%ignore_rlof = false, but it 
> appears to be insufficient. What other conditions should I configure?
>
>  The specific code is as follows：
>
>        if (b% rl_relative_gap(1) > 0 .and. b% rl_relative_gap(2) > 0 
> .and. &
>
>        log10(abs(b% mtransfer_rate)/Msun*secyer) > -40 .and. b% m(b% 
> a_i) > b% m(b% d_i)) then
>
>           b% ignore_rlof = .true.
>
>        endif
>
> Thank you for your time and consideration.
>
> Best regards,
>
> Levi
>
>
> _______________________________________________
> mesa-users at lists.mesastar.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users
>

-- 
Mathieu Renzo <https://users.flatironinstitute.org/~mrenzo/>
Flatiron Research Fellow
Center for Computational Astrophysics
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