[mesa-users] helium main sequence binary

Sat Sep 12 12:46:37 EDT 2015

Hi Josiah, Ying.

This is effectively undesired behaviour. MESAbinary simply calls the relax
routines in the star module, it is there that things like winds are turned
off during the relaxation process. These routines are in
star/private/relax.f90, winds are turned off by the subroutine
turn_off_winds, and the subroutines save_stuff and restore_stuff save and
restore the user provided values before and after the relaxation process.

As you can see, there is nothing done there for use_other_wind, so all
relaxation routines should have the same problem. The fix is pretty
straightforward, but for some weeks im on smartphone-only mode, so doing
changes is a bit hard for me. Unless someone else makes the change and
commits it, it will have to wait until I have access to a proper laptop.

For the moment Jing, I'd recommend what Josiah says, just run 1 model with
the wind turned off, save it, and then restart with the wind on.
Am 12.09.2015 7:08 nachm. schrieb "Ying Qin" <Ying.Qin at unige.ch>:

> Hi Josiah,
>
> Thank you very much for quick reply. I now understand what some parameters
> really mean.
>
> I update my binary/work and use some parameters by default. The wrong
> results should be due to the settings in a not correct way I used.
> And now it works well.
> model_number     age                                           period_days
>                               binary_separation
> star_1_mass                                   lg_mstar_dot_1
>           1                3.1622776601683819E+002
> 2.0502586561339722E-001     3.2807055306783051E+000
>  9.8803896662487389E+000         -4.2110699139184131E+000
> The results are reasonable now. I just ran it for about 20 mins, and I
> want to run it in a longer time, and see what’s going on.
>
> BTW:
> 1. About inlist1, I use some parameters by default, and add one command
> line: mesa_dir = ‘ ‘. It seems to use mesa r-7624 environment.
> So can you please explain more about this command ?
>
> 2. How to make mesa run fast ? I though one way is to change the
> time_step, are there any other controls ?
>
>
> l put the new inlists below if you want to check.  Your reply helped
> indeed, and thank you so much again.
>
> Have a nice day,
> Ying
>
>
>
> On 12 Sep 2015, at 17:29, Josiah Schwab <jwschwab at berkeley.edu> wrote:
>
> Hello Ying,
>
> On 12 September 2015 at 03:37 PDT, Ying Qin wrote:
>
> Thank you for sending the additional files.  Now I can reproduce the
> results you mention.
>
> I know WR star lost mass very fast, these results are not what I expect
> now.
> Why does WR star decrease mass from 3.9637246692135668E+000 ? I think the
> mass of WR should be decreasing from about 10.0.
> Why does binary_separation change from 9.6975446700026726E+000 ? Because I
> initialize this it with 0.2d0.
> For these results, I said there were random, Because they are not
> reasonable.
>
>
> Before the main evolution begins, there was a relaxation stage to
> satisfy the condition that the rotation of the star be sychronized with
> the orbit (since you specified do_initial_orbit_sync_1 = .true.).
>
> During this part --- which is printed to your terminal along with some
> relax_to_omega messages, but is not included in the binary_history.data
> file --- the WR wind you specified was active.  So by the time the
> system gets synchronized and therefore ready for the main evolution, the
> star has lost mass and the orbit has adjusted.
>
> I'm surprised (as are you) that MESA isn't deactivating mass loss during
> this relaxation phase.  Hopefully Pablo or one of the binary experts can
> chime in.
>
> I suggest the following work-around.  Make a tidally synchronized model
> by running with the WR wind off.  Immediately save this model at
> timestep 1.  Then load this saved model and run with the WR wind on.
>
>
> Also, I want star1 to evolve with zero age and zero model number, and
> I change these in inlist1:
>
>      set_initial_age = .true.
>      initial_age = 0 ! in years
>
>      set_initial_model_number = .true.
>      initial_model_number = 0
>
> But from the results, we can clearly find it did not  work.
>
>
> These controls are mainly used when you are loading a saved model file,
> which has an associated age and model number.  These controls are not
> really relevant since your model is coming from one of the ZAMS files.
>
> Still, why is it clear this "didn't work"?
>
> When I look in binary_history.data, the first model number is 1 and the
> first star_age is the duration of the first timestep.  That is what I
> would expect to see using these flags (even if it is not really due to
> these flags in this case).
>
> Hope that helps,
> Josiah
>
>
>
>
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