MESAHub · Debraheem · May 15, 2026 · May 16, 2026 · May 16, 2026 · May 18, 2026
@@ -46,6 +46,8 @@ Bug Fixes
 
 Important bug fix for ``r26.4.1`` identified by Emily Sandford and Louis Siebenaler: the ``lowT_Freedman11`` opacity option used ``[M/H]`` labels as the metal mass fraction when interpolating in ``Z``, resulting in incorrect opacities. We recommend users who use these low-temperature opacities, such as in planet models, update to the latest MESA version or employ the fixes in :ref:`the known bugs entry <freedman_lowt_z_bug>` and `gh-993 <https://github.com/MESAHub/mesa/pull/993>`_.
 
+The plasmon neutrino cooling rate used a 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 plasmon neutrinos. This affects all previous MESA versions, and was found and fixed by user Garv Chauhan, see :ref:`the known bugs entry <plasmon_weinberg_angle_bug>` and `gh-998 <https://github.com/MESAHub/mesa/pull/998>`_. Plasmon neutrinos now use the same Weinberg angle as all other processes and changing its value will affect the corresponding cooling rate. Changes to the plasmon neutrino prefactor for MESA's default Weinberg angle result in small numerical differences for stars where plasmon neutrino cooling is significant.
+
 Fixed a bug where RSP photo restarts did not immediately reconstruct ``s% L``,
 which could leave ``s% L(1)`` with an uninitialized near-zero value and crash
 MESA when the KH timescale was recalculated on restart.

@@ -13,6 +13,22 @@ issue, but it may not be complete.
 r26.4.1
 =======
 
+.. _plasmon_weinberg_angle_bug:
+
+Neu: plasmon neutrino cooling used a hardcoded Weinberg angle
+-------------------------------------------------------------
+
+The plasmon neutrino cooling rate used a 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 plasmon neutrinos.
+
+This affects all released MESA versions through ``r26.4.1`` and was found and
+fixed by user Garv Chauhan in `gh-998 <https://github.com/MESAHub/mesa/pull/998>`_.
+Plasmon neutrinos now use the same Weinberg angle as all other processes, and
+changing its value will affect the corresponding cooling rate. Changes to the plasmon neutrino prefactor for MESA's default Weinberg angle result in small numerical differences for stars where plasmon neutrino cooling is significant.
+
 .. _freedman_lowt_z_bug:
 
 Kap: ``lowT_Freedman11`` used ``[M/H]`` labels as ``Z``

@@ -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
@@ -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
@@ -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
@@ -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

@@ -138,7 +138,7 @@
 
       ! you might want to get a more complete list of mixing regions by using the following
 
-      !mixing_regions <integer> ! note: this includes regions where the mixing type is no_mixing.
+      mixing_regions 20 ! note: this includes regions where the mixing type is no_mixing.
 
          ! the <integer> is the number of regions to report
          ! there will be 2*<integer> columns for this in the log file, 2 for each region.
@@ -340,7 +340,7 @@
 
       ! you might want to get a more complete list of burning regions by using the following
 
-      !burning_regions <integer>
+      burning_regions 20
          ! the <integer> is the number of regions to report
          ! there will be 2*<integer> columns for this in the log file, 2 for each region.
          ! the first column for a region gives int(sign(val)*log10(max(1,abs(val))))

@@ -38,8 +38,7 @@
       set_initial_model_number = .true.
       initial_model_number = 0
 
-      pgstar_flag = .false.
-      !pgstar_flag = .true.
+      pgstar_flag = .true.
 
 / ! end of star_job namelist
 
@@ -219,6 +218,7 @@
       warn_rates_for_high_temp = .true.
       max_safe_logT_for_rates = 10.5d0
 
+      use_superad_reduction = .true. 
 
       Pextra_factor = 2 ! for atm
 

@@ -22,7 +22,7 @@
       new_cumulative_energy_error = 0d0
 
       set_initial_dt = .true.
-      seconds_for_initial_dt = 1d-8
+      seconds_for_initial_dt = 1d-4
 
       set_initial_model_number = .true.
       initial_model_number = 0