[Mesa-users] About nse.net

[Rob Farmer]

Hi Wenyu,

The likely problem you have is that with nse.net you are running into the
rate 55cu(g,p)54ni which is an exothermic photo disintegration.

In mesa 12778 this is not handled properly. We would use what reaclib
stated was the forward rate to compute the reverse rate in detailed
balance. However this definition is wrong for exothermic photo
disintegrations leading to bogus rates which causes the solver issues (the
rate is ~10^100 at low temperatures and decreases with temperature!).

The solution is to upgrade to mesa 15140 where this is fixed (by ignoring
what reaclib says and defining the reverse rate as the endothermic
reaction).

Rob

On Mon, 13 Dec 2021 at 18:30, Francis Timmes via Mesa-users <
mesa-users at lists.mesastar.org> wrote:

> hi wenyu,
>
> 5e9 k is probably too hot to be mapping in a change in the reaction
> network.
> perhaps try changing the network when the central temperature is a bit
> cooler, say 2e9 k.
>
> fxt
>
>
>
>
>
> > On Dec 12, 2021, at 9:30 PM, 辛文宇 via Mesa-users <
> mesa-users at lists.mesastar.org> wrote:
> >
> > Dear everyone,
> >
> >
> >
> > I use the example of "25M_pre_ms_to_core_collapse" in 12778 version to
> evolve stars
> >
> > from ZAMS to Fe core collapse. When the central T reaches 5E+9 (log
> Tc=9.7), I want
> >
> > change the nuclear network into "nse.net". The network in the former
> stages I used is
> >
> > mesa_128.net. The former evolution is smoothly. However, when the
> network changes
> >
> > to nse.net. The following problem is shown:
> >
> > ======================================================================
> >
> >  netint failed: abs(h).lt.stpmin   3.4753213900951310E-029
>  9.9999999999999997E-029
> >  netint failed: abs(h).lt.stpmin   2.8806830949925469E-029
>  9.9999999999999997E-029
> >  retry    1012
> >                            1st model retry log10(dt/yr)
>  -1.9254117971048657D+01
> >  netint failed: abs(h).lt.stpmin   3.4753213900951310E-029
>  9.9999999999999997E-029
> >  netint failed: abs(h).lt.stpmin   2.8806830949925469E-029
>  9.9999999999999997E-029
> >  retry    1012
> >                                                      dt
> 8.7894878303463986D-13
> >                                      min_timestep_limit
> 9.9999999999999998D-13
> >
> >  stopping because of problems dt < min_timestep_limit
> >
> >  terminated evolution: cannot find acceptable model
> >
> >  termination code: min_timestep_limit
> >
> > ======================================================================
> >
> > The inlist file the detail output information file are attached.
> >
> > I am not sure how to modify the file and makes the evolution
> >
> > successfully.
> >
> >
> >
> > Thanks,
> >
> > Wenyu
> >
> >
> >
> >
> <inlist_to_lgT_9.7><inlist_to_lgT_9.9><slurm-364461.out>_______________________________________________
> > mesa-users at lists.mesastar.org
> > https://lists.mesastar.org/mailman/listinfo/mesa-users
> >
>
> _______________________________________________
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>
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