[Mesa-users] Power or rate of specific (weak) reactions

[Diogo Capelo]

Greetings MESA users,

Since this e-mail got a little long-winded, I'll start with my question 
and, if you feel relevant, you can check the context of it below:

Is there a way to access the power (erg/g/sec) or rate of specific 
reactions (specifically, weak reactions like r_b8_wk_he4_he4) directly 
without resorting to run_star_extras.f?

--- Context ---

I'm currently working on a project focused on studying neutrino 
oscillations inside stars, and it would be interesting to me to be able 
to plot not only the total neutrino losses (or power) with respect to 
the radius - the relevant variables for which can be extracted directly 
from the profile_columns.list - but to actually identify the source of 
the neutrinos and reconstruct the emission spectra. I've had some fun 
reading past replies to this mailing list regarding similar questions 
(like this one: 
https://lists.mesastar.org/pipermail/mesa-users/2015-September/005647.html) 
and figuring out how MESA works, and understand that my ultimate goal 
will require some (or, more likely, a lot of) effort. If I've understood 
correctly, MESA calculates the (average) neutrino energy, Qneu, for each 
reaction, such that reconstruction of the energy-flux spectra requires 
some adjustments to the neutrino routines (and possibly the tables too).

So, as a first approach, and as a way to familiarize myself with the 
fortran language and the MESA organizational structure, I've been trying 
to do something less ambitious, which requires getting the power/rates 
for the neutrino-relevant reactions. On one of my "legacy" versions of 
MESA (it's one of the r-7* versions, not sure exactly which) I have a 
work directory, previously modified by someone else, where I can read, 
in the profile_columns.list:

    ! ergs/g/sec for specific reactions (names from rates_def)
       !rpp

(It's in line 219 in my file, but I've changed the order of a few 
variables for ease of reading, so that probably won't translate very 
well into anyone else's files).

After identifying the reactions in rates_def.f and adding them to 
profile_columns.list, I get the following error:

  bad profile list name: r_pep_to_h3
  bad profile list name: r_pp_to_h3
  bad profile list name: r_be7_wk_li7
  bad profile list name: r_b8_wk_he4_he4
  bad profile list name: r_h1_he3_wk_he4
  star_set_profile_columns ierr          -1
  do_star_job_controls_after ierr          -1
  before_evolve_loop ierr          -1

The first few lines correspond to some of the reactions I'm trying to 
get information about. I've tried several variations of the names (with 
and without underscores, calling them by their index numbers, etc.) but 
I always seem to get the same errors back. This seems to indicate that I 
either got the reaction names wrong or that the control is inexistent in 
my version.

Then, I looked at the default profile_columns.list file in 
star/defaults/, where I found the usual commented section to add the 
power of specific reaction *categories* (line 414) but not for specific 
reactions, which led me to my original question (I checked on r-10398 
and it's absent from there as well). I'd be inclined to think that it 
either has been removed or never existed in the first place and the 
lines were included by mistake or never meant to be uncommented, but 
then I found, in star_data.inc, variables to save the flux of specific 
reaction neutrinos (flux_pp, flux_pep, etc.) at 1 AU, which seem to 
indicate that there *could* be some way already in place for MESA to 
discriminate the source of neutrino emissions (though these could just 
be estimations calculated from source abundances and total neutrino 
luminosity), which made me doubt again, even if printing these variables 
seemed to return always 0 for the cases I tried.

Any help or clarification you could provide would be greatly 
appreciated. And thank you, by the way, for all the resources available 
online for learning how to use (and tinker with) MESA. They are 
fantastic.


Thank you for your time,
Diogo Capelo