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

[Francis Timmes]

hi jason,

if this remains an issue, send the ns_env.mod and ns_he_hstatic.mod files.

fxt





> On Oct 26, 2022, at 11:06 AM, Pero, Jason via Mesa-users <mesa-users at lists.mesastar.org> wrote:
> 
> Hello MESA users,
> 
> MESA version r22.05.1
> inlists attached
> 
> 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.
> 
> 
> Jason Pero
> Graduate Research Assistant
> University of Texas at Arlington​<inlists.zip>_______________________________________________
> mesa-users at lists.mesastar.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users