[Mesa-users] Inquiry about Units in profile.data

[Diogo Capelo]

Greetings,

That will depend on the version of MESA you're using. In the newer 
versions of MESA (23 and 24), the reaction rates you can output directly 
from profile_columns.list are in units of (s^-1). However, the default 
names of the columns don't match the one you use.

The name you use suggests to me (but I may be mistaken) that you are 
using an older version (pre-23) of MESA with a custom piece of code in 
run_star_extras to read out the reaction rates. In this case, the 
documentation on the "rate_screened" variable (which is the one likely 
being read and printed) is defined in 
"$MESA_DIR/net/public/net_def.f90", where you can read:

"The units here depend on the number of reactants. In all cases, the 
rate_screened times as many molar fractions as there are reactants gives 
a number with the same units as dy/dt. So for a 2body reaction, there 
are 2 Y factors, each with units [moles/gram] and the rate_screened 
units for such a reaction are [grams/(mole sec)], which when multiplied 
by [moles/gram]^2 gives the same units as dydt. For a 1body reaction 
(e.g., a decay), there is only 1 Y factor, so the units are [1/second]. 
Similarly, a 3body reaction will have rate_screened with units of 
[gram^2/(mole^2sec)]."

I would advise checking whether you're writing the rates into the 
profile directly or whether you're outputting them via run_star_extras 
and, in the latter case, checking which variable is being passed onto 
the profile, and then tracking down that variable in the MESA files.

Hope this helps!

-- 

Diogo

A 2025-02-17 09:25, Guo Li via Mesa-users escreveu:

> Hi all,
> 
> I hope this message finds you well.
> 
> I am currently analyzing the profile.data file and would like to 
> inquire about the units for the reaction rate column, such as 
> log_rate_r_c12_ag_o16.
> 
> Thank you for your support!
> 
> Best regards,
> Guo Li
> National Astronomical observatories,CAS
> 
> _______________________________________________
> mesa-users at lists.mesastar.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20250217/f5efea13/attachment.htm>