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

[ABHIJNAN KAR 20064]

A gentle reminder!

> On 12-Jul-2023, at 12:45 AM, Pulkit Ojha <pulkit.ojha at niser.ac.in> wrote:
> 
> 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 <mailto: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 <mailto: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$>
>>> Bhubaneswar, INDIA
>>> 
>>> 
>>> 
>>> _______________________________________________
>>> mesa-users at lists.mesastar.org <mailto:mesa-users at lists.mesastar.org>
>>> https://urldefense.com/v3/__https://lists.mesastar.org/mailman/listinfo/mesa-users__;!!IKRxdwAv5BmarQ!dPs0I_NtKoQRnpfmatdrcvp3atkIEBt9Cn2kPKqPIy-lnf3EwwHGazY74Dp19ztpDcIcxkwWPxnEGTAAm0IMGyGA$ 
>>> 
> 
> 
> -- 
> Pulkit Ojha
> 5th Year Integrated MSc.,
> School of Physical Sciences,
> National Institute of Science Education and Research <https://www.niser.ac.in/>
> Bhubaneswar, INDIA
> 
> <snippet_MESA__run.png><data_compare_mb_on_and_off.zip>

Regards,
Abhijnan Kar(He/his/him)
BS-MS,IISER Berhampur






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