[Mesa-users] Electron Capture in High Density Regimes

[Josiah Schwab]

Hi Joe,

Does MESA include electron captures, i.e. inverse beta decay, in its
> reaction calculations?  I can see from the docs,
>
>
> https://docs.mesastar.org/en/latest/reference/star_job.html?highlight=beta#use-suzuki-weak-ratesthere
>
> there are provisions for using special rates, but I’m wondering if there
> is a particular reaction library that most be chosen, so some other
> configuration that must be used to include them.
>

MESA includes electron capture reactions if the nuclear network includes
the relevant isotopes and reactions (and if we have rate data for that
reaction).

You can see the isos and reactions in your net with the star job flags

    show_net_species_info = .true.
    list_net_reactions = .true.

In some cases you may need to add isotopes/reactions to your network to get
what you want.  For example, ne23, the neutron-rich daughter of na23 is
often not in nets by default since the high density conditions where it's
relevant aren't typical.

You can set the standard MESA collection of weak rates
in data/rates_data/weakreactions.tables (plus the weak reactions that are
in JINA REACLIB).

The Suzuki et al. (2016) rates replace the default collection of rates for
the sd-shell nuclei with a more densely tabulated set, which is especially
important in cooler conditions.   (I'm guessing you're interested in Mch
WDs, so you probably do want to use these.)

I can give more detailed advice if you have a specific application in mind.

Josiah
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