[Mesa-users] Heavy rotation in massive stars

Francis Timmes fxt44 at mac.com
Sat Aug 20 13:09:47 UTC 2022


hi amar,

there might be some confusion on what new_omega_div_omega_crit does and does not do.

the plot shows that a perturbation imposed on an equilibrium model experiences a transient response before the system settles into a new equilibrium configuration. this is what is supposed to happen. that perturbation, generated all-at-once or via relaxation from the inlist options, merely sets an initial condition. new_omega_div_omega_crit is not a guarantee of post-transient equilibrium model values, nor a condition imposed at every timestep.

fxt




> On Aug 19, 2022, at 12:09 PM, amar at aries.res.in wrote:
> 
> Dear Prof. Timmes,
> 
> Thank you for the suggestion and the thread link. To improve the temporal resolution, I recalculated the model using time_delta_coeff = 0.1 and the result for rotation is shown in attached figure. Later, I also used the suggestions provided in the quoted thread and set: max_years_for_timestep = 1.0 with do_adjust_J_lost = .false. But, due to this, the evolution seems to proceed in steps of one year and the evolution to ZAMS continued to run (I terminated the run at model no 174,000 by pressing ctrl+Z). Further, I also tried with max_years_for_timestep = 1000 and max_years_for_timestep = 100 and plotted the results for rotation as attached. Unfortunately, the results are still similar to the earlier cases with surf_avg_omega_div_omega_crit touching 1, only for a shorter period and remaining < 1 for most of the evolution.
> 
> Any further suggestions could be very helpful for me.
> 
> With best regards,
> Amar
> 
> 
> ----- Original Message -----
> From: fxt44 at mac.com
> To: amar at aries.res.in
> Cc: fxt44 at mac.com, mesa-users at lists.mesastar.org
> Sent: Thursday, August 18, 2022 10:59:04 PM
> Subject: Re: [Mesa-users] Heavy rotation in massive stars
> 
> hi amar,
> 
> i suspect the issue is the same as in the recently posted
> 
> https://lists.mesastar.org/pipermail/mesa-users/2022-August/013973.html
> 
> that is, insufficient timestep resolution to observe the initial imposed rotation profile evolve.
> 
> fxt
> 
> 
> 
> 
>> On Aug 18, 2022, at 2:34 AM, Amar Aryan via Mesa-users <mesa-users at lists.mesastar.org> wrote:
>> 
>> Dear mesa user,
>> 
>> MESA_VERSION : mesa-r22.05.1
>> OS : Ubuntu 20.04
>> 
>> I am trying to evolve a heavily rotating 25 M_sun ZAMS star up to the stage of core-collapse by setting new_omega_div_omega_crit = 1.0 in inlist_mass_Z_wind_rotation. The model could successfully evolve up to the desired stage. Just to check if the rotation has been implemented correctly or not, I plotted "surf_avg_omega_div_omega_crit" against "star_age" when the run has finished inlist_to_zams.  From the attached plot, I could see that the "surf_avg_omega_div_omega_crit'' has almost never touched the value of 1.0! 
>> <rotation.png>
>> 
>> So, I am just wondering if the rotation has been correctly employed in the model or not. Also, Is it because the "surf_avg_omega_div_omega_crit"  represent the average value of "omega_div_omega_crit" at the surface? I am using satisfactory temporal and spatial resolution by setting :  time_delta_coeff = 0.8, varcontrol_target   = 1d-3, mesh_delta_coeff = 0.7, and mesh_delta_coeff_for_highT = 0.9.
>> 
>> Please provide your suggestion.
>> 
>> With regards,
>> Amar
>> 
>> 
>> _______________________________________________
>> mesa-users at lists.mesastar.org
>> https://lists.mesastar.org/mailman/listinfo/mesa-users
>> 
> <rotation.png>



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