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Minor Changes to Neutrino Cooling Rate #998

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Merged
Debraheem merged 4 commits into from
May 18, 2026
+13 −6
Merged

Minor Changes to Neutrino Cooling Rate #998

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0108873
Changes to Neutrino Cooling Rate File
gchauhan42 May 15, 2026
7e66562
Merge pull request #1 from gchauhan42/gchauhan42-NeutrinoFix
gchauhan42 May 15, 2026
1f9f34b
Add to changelog the Weinberg angle change
mathren May 16, 2026
e9fb16e
link to PR
mathren May 16, 2026
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6 changes: 6 additions & 0 deletions docs/source/changelog.rst
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Expand Up @@ -35,6 +35,12 @@ MESA no longer stops when reactions for which special rates are set are not in t
Bug Fixes
---------

The plasma neutrino cooling rate was using an hardcoded prefactor calculated with a Weinberg angle of 0.2319, while all other neutrino cooling processes used calculated prefactors taking the Weinberg angle as input, with default value 0.22290.
Thus, modifying the value of the Weinberg angle resulted in changes to neutrino cooling processes except for the plasma neutrinos.
This was the case in all previous MESA versions, and was found and fixed by user Garv Chauhan, see `gh-998 https://github.com/MESAHub/mesa/pull/998`_. Plasma neutrinos now use the same Weinberg angle as all other processes and changing its value will affect the corresponding cooling rate.
The change in default Weinberg angle results in small numerical differences for stars where plasma neutrino cooling is significant.


The parameter ``report_max_infall_inside_fe_core`` was ignored in versions r25.12.1 and r26.4.1 and always had it's default value. See `gh-981 https://github.com/MESAHub/mesa/pull/981`_.

``fe_core_infall_limit`` now obeys ``when_to_stop_rtol`` and ``when_to_stop_atol`` again (broken since r11532).
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13 changes: 7 additions & 6 deletions neu/private/mod_neu.f90
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Expand Up @@ -35,6 +35,7 @@ module mod_neu
real(dp), parameter :: cvp = 1.0d0 - cv
real(dp), parameter :: ca = 0.5d0
real(dp), parameter :: cap = 1.0d0 - ca
real(dp), parameter :: tfac0 = cv*cv + (num_neu_fam-1.0d0) * (cvp*cvp)
real(dp), parameter :: tfac1 = cv*cv + ca*ca + (num_neu_fam-1.0d0) * (cvp*cvp+cap*cap)
real(dp), parameter :: tfac2 = cv*cv - ca*ca + (num_neu_fam-1.0d0) * (cvp*cvp - cap*cap)
real(dp), parameter :: tfac3 = tfac2/tfac1
Expand Down Expand Up @@ -237,13 +238,13 @@ subroutine neutrinos(T, logT, Rho, logRho, abar, zbar, log10_Tlim, &
temp = T
end if

if (T <= 0) then
if (temp <= 0) then
info = -1
return
end if

if (logT == arg_not_provided) then
logtemp = log10(T)
logtemp = log10(temp)
else
logtemp = logT
end if
Expand All @@ -263,13 +264,13 @@ subroutine neutrinos(T, logT, Rho, logRho, abar, zbar, log10_Tlim, &
den = Rho
end if

if (Rho <= 0) then
if (den <= 0) then
info = -1
return
end if

if (logRho == arg_not_provided) then
logden = log10(Rho)
logden = log10(den)
else
logden = logRho
end if
Expand Down Expand Up @@ -1579,8 +1580,8 @@ subroutine plas_neu(splas,splasdt,splasdd,splasda,splasdz, input)
splasdz = a2*splasdz + a3*gl2dz*a1


a2 = 0.93153d0 * 3.0d21 * input% xl9
a3 = 0.93153d0 * 3.0d21 * 9.0d0*input% xl8*input% xldt
a2 = tfac0 * 3.0d21 * input% xl9
a3 = tfac0 * 3.0d21 * 9.0d0*input% xl8*input% xldt

a1 = splas
splas = a2*a1
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