[Mesa-users] Neutron star wind model: Tau Factor

Francis Timmes fxt44 at mac.com
Wed Oct 26 15:28:26 UTC 2022

hi jason,

there is not enough information provided for anyone to maybe offer guidance.
at minimum, the inlist should be provided.

in the future, please do not post hundreds of lines of mesa terminal output.
either attach the output as a plain text file, or select a few lines from 
the terminal output that succintly summarize the situation.


> On Oct 24, 2022, at 5:59 PM, Pero, Jason via Mesa-users <mesa-users at lists.mesastar.org> wrote:
> Hello MESA users,
> MESA version r22.05.1
> I'm having trouble simulating the hydrodynamic phase of a neutron star x-ray burst. During the hydrostatic rise the tau_factor is set to a value similar to what is in the ns_he test suite:
> set_initial_tau_factor = .true.
> set_to_this_tau_factor = 100
> During the wind phase I switch from the hydrostatic to the hydrodynamic solver at which time a change the tau_factor to capture regions closer to the photosphere:
> relax_initial_tau_factor = .true.
> relax_tau_factor = .true.
> relax_to_this_tau_factor = 1
> Running the hydrodynamic phase then produces the following error:
> stopping because of problems dt < min_timestep_limit
>  failed in relax tau factor
>  star_relax_tau_factor ierr          -1
> I've tried different tau factors ranging from 1-99 and still no luck. Based on the debug information it looks like there is an issue with the density becoming unrealistic. I then tried adjusting the control options "min_timestep_limit" and "hydro_mtx_max_allowed_logRho", but still can't get the model to relax to the new tau factor. 
> Any help/advice would be greatly appreciated.
> Here is the full debug output from the terminal:
> ... snip ...
> Jason Pero
> Graduate Research Assistant
> University of Texas at Arlington​
> _______________________________________________
> mesa-users at lists.mesastar.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users

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