[Mesa-users] A Query regarding swithcing off magnetic braking

[Pulkit Ojha]

Hello,
Thank you for your reply.

I'm using MESA version r22.05.01. I do not have any desired stopping
condition. In my runs, the evolution stops when the donor mass becomes very
small and software isn't able to find any consistent solution, stating "dt
< min_timestep_limit" or "no. of redo exceeding redo_limit".

In the case of "keep_mb_on = .true." , it is true that the timestep becomes
so small after first 5k+ steps. I'm attaching binary_history files for both
the cases and the same set of initial parameters. I'm also attaching a
snippet of terminal output of MESA run with "keep_mb_on = .true." .

Truly
Pulkit

On Tue, Jul 11, 2023 at 12:06 AM Ebraheem Farag <ekfarag at asu.edu> wrote:

> Hello Ojha,
>
> Would you mind sharing which version of MESA you are using?
>
> What is your desired stopping condition?
>
> > but if case we do not switch it off i.e. "keep_mb_on = .true."
> , evolution isn't stopping at all. After running for 12-13k steps, the mass
> transfer rate as well as the masses of both the stars become constant but
> the steps are just repeating themselves, even till 40k steps.
>
> It sounds like your timesteps have become very small. Can you comment on
> the difference in time step size between both runs with and without  "keep_mb_on
> = .true." ? Are the size of timesteps different between runs? What is
> controlling the timesteps in your terminal output in both runs? A short
> print out attachment of a snippet from your terminal output would be useful.
>
> Thanks,
> EbF
>
>
> On Sun, Jul 9, 2023 at 12:16 AM Pulkit Ojha via Mesa-users <
> mesa-users at lists.mesastar.org> wrote:
>
>> Dear All,
>>
>> I'm evolving LMXB models with NS accretors with the specifications
>> described in the attached inlist_project file. There is this option of
>> "keep_mb_on" for calculating the angular momentum loss due to magnetic
>> braking. It decides whether to switch off magnetic braking when the star
>> becomes fully convective. If we choose to switch it off, models are running
>> fine (stopping after 5-8k timesteps) but if case we do not switch it off
>> i.e. "keep_mb_on = .true." , evolution isn't stopping at all. After running
>> for 12-13k steps, the mass transfer rate as well as the masses of both the
>> stars become constant but the steps are just repeating themselves, even
>> till 40k steps.
>>
>> Can anyone help me to understand what's going on there? Is the software
>> getting stuck in some loop or the values of mass transfer become so low
>> that they do not appear changing?
>> Please find attached the inlist and extras files.
>>
>> --
>> Pulkit Ojha
>> 5th Year Integrated MSc.,
>> School of Physical Sciences,
>> National Institute of Science Education and Research
>> <https://urldefense.com/v3/__https://www.niser.ac.in/__;!!IKRxdwAv5BmarQ!dPs0I_NtKoQRnpfmatdrcvp3atkIEBt9Cn2kPKqPIy-lnf3EwwHGazY74Dp19ztpDcIcxkwWPxnEGTAAm7DH0uOT$>
>> Bhubaneswar, INDIA
>>
>>
>> _______________________________________________
>> mesa-users at lists.mesastar.org
>>
>> https://urldefense.com/v3/__https://lists.mesastar.org/mailman/listinfo/mesa-users__;!!IKRxdwAv5BmarQ!dPs0I_NtKoQRnpfmatdrcvp3atkIEBt9Cn2kPKqPIy-lnf3EwwHGazY74Dp19ztpDcIcxkwWPxnEGTAAm0IMGyGA$
>>
>>

-- 
Pulkit Ojha
5th Year Integrated MSc.,
School of Physical Sciences,
National Institute of Science Education and Research
<https://www.niser.ac.in/>
Bhubaneswar, INDIA
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20230712/8342d5f1/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: snippet_MESA__run.png
Type: image/png
Size: 184797 bytes
Desc: not available
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20230712/8342d5f1/attachment-0001.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: data_compare_mb_on_and_off.zip
Type: application/zip
Size: 3891842 bytes
Desc: not available
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20230712/8342d5f1/attachment-0001.zip>