[Mesa-users] the weak nuclear reaction rate in "other"

[Ebraheem Farag]

Hello Yunlang,

"However, I found that the "other" reaction rate calculated by the code is
inconsistent with the "other" output by MESA's profile.

Doesn't this code work for weak reactions?"
The subject of the thread you shared pertains to the run_star_extras
previously shared by Frank available here: timmes_eps_nuc_from
specific_reactions <https://zenodo.org/record/3372837#.ZDZ4Hy-B3qB>.
It does not work for weak reactions taken from weaklib.

This routine uses the 'net_get' subroutine from net_lib.f , see line
236 in timmes_eps_nuc_from
specific_reactions <https://zenodo.org/record/3372837#.ZDZ4Hy-B3qB>. The
'net_get' subroutine returns 'std_reaction_Qs, std_reaction_neuQs', which
do not include values from weaklib and instead pulls values for weak
reactions directly from $MESA_DIR/data/rates_data/ 'reactions.list' and
'weak_info.list' . To get the actual values for weak reactions from
weaklib, you need to substitute the 'net_get' subroutine in this
run_star_extras for 'net_get_with_Qs' which can also be found in net_lib.f
(I'm not certain, but it should exist in r10398). The 'net_get_with_Qs'
subroutine will return 'actual_Qs' and 'actual_neuQs' from weaklib which
can be used to correctly calculate the energy generation rate for weak
reactions in place of 'std_reaction_Qs' and 'std_reaction_neuQs'. You need
to define these pointers in your run_star_extras.f before calling them into
this subroutine like so:



    *real*(dp), *target*, *dimension*(:) :: actual_Qs(num_reactions)
!=>NULL()

    *real*(dp), *target*, *dimension*(:) :: actual_neuQs(num_reactions)
!=>NULL() ! ignore if null  (num_reactions)

    *logical*, *target* :: from_weaklib(num_reactions)!


 for whatever the value of the number of reactions are in your current net,
num_reactions:

--------------------------------
Another option to easily get these values out of a MESA model is to move to
revision 22.11.1 of MESA in which Rob Farmer and Earl Bellinger worked hard
to add profiles_columns and history_columns that enable you to output
information on individual reactions without having to touch the
run_star_extras.

>From history_columns.list in r22.11.1:

   !## information about individual reactions
          ! adds columns for all of the reactions that are in the current
net
      ! Note that if using op_split_burn=.true. then zones which have been
split will report 0 for their rates
      !add_raw_rates      ! raw reaction rates,       reactions/second
      !add_screened_rates ! screened reaction rates reactions/second
      !add_eps_nuc_rates  ! Nuclear energy (minus neutrino losses) released
  erg/s
      !add_eps_neu_rates  ! Neutrino losses             erg/s

          ! individual reactions (as many as desired)
          ! use list_net_reactions = .true. in star_job to list all
reactions in the current net
          ! reactions/second
      !raw_rate r_h1_h1_ec_h2
      !raw_rate r_h1_h1_wk_h2

>From profile_columns.list in r22.11.1:

   ! adds columns for all of the reactions that are in the current net
   ! Note that if using op_split_burn=.true. then zones which have been
split will report 0 for thier rates
   !add_raw_rates      ! raw reaction rates,       reactions/second
   !add_screened_rates ! screened reaction rates reactions/second
   !add_eps_nuc_rates  ! Nuclear energy (minus neutrino losses) released
erg/s
   !add_eps_neu_rates  ! Neutrino losses             erg/s

   ! individual reactions (as many as desired)
   ! use list_net_reactions = .true. in star_job to list all reactions in
the current net
   ! reactions/second
      !raw_rate r_h1_h1_ec_h2
      !raw_rate r_h1_h1_wk_h2


Hope this helps.

-EbF

On Wed, Apr 12, 2023 at 1:53 AM 郭云浪 <yunlang at ynao.ac.cn> wrote:

> Dear MESA-users,
>
>
> How to get the energy (erg/g/s) released by the weak nuclear reaction
> classified as "other" in MESA-r10398？
>
> such as Urca reaction:
>
>                r_na23_wk_ne23
>                r_ne23_wk-minus_na23
>                r_ne23_wk_f23
>                r_f23_wk-minus_ne23
>                r_mg25_wk_na25
>                r_na25_wk-minus_mg25
>                r_na25_wk_ne25
>                r_ne25_wk-minus_na25
>
>
> In the previous email, I knew how to obtain the nuclear reaction rate of nuclear
> reaction, e.g. r_he4_he4_he4_to_c12, r1212,
>
> see https://lists.mesastar.org/pipermail/mesa-users/2022-April/013605.html
> <https://urldefense.com/v3/__https://lists.mesastar.org/pipermail/mesa-users/2022-April/013605.html__;!!IKRxdwAv5BmarQ!bpohl6_gepYEXDkClma0AjytsbAS7gg8QCIRU6NFs6tNP_ttuF0g_0nGzq3YqYA2me8XRa5z4Itwp_4XQg$>
> .
>
>
> However, I found that the "other" reaction rate calculated by the code is
> inconsistent with the "other" output by MESA's profile.
>
>
> Doesn't this code work for weak reactions?
>
>
> _______________________________________________
> mesa-users at lists.mesastar.org
>
> https://urldefense.com/v3/__https://lists.mesastar.org/mailman/listinfo/mesa-users__;!!IKRxdwAv5BmarQ!bpohl6_gepYEXDkClma0AjytsbAS7gg8QCIRU6NFs6tNP_ttuF0g_0nGzq3YqYA2me8XRa5z4Ivs8xWrUg$
>
>
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