nulosses.f

97 lines · 2 definitions · on GitHub (7be4133)

Python version: nulosses.py, 65 lines, on the right (switch to Python above the code).

Purpose

A thin wrapper, "modified by G. Newsham from codes of N. Itoh & F. Timmes (9/06)": it computes the composition's mean nucleon number $\bar A$ and charge $\bar Z$, and passes them to SNEUT, which computes the neutrino losses. The header notes that only the carbon coefficients are used for bremsstrahlung losses ("the differences for other elements is slight"), and that the cutoff at $0.01\,T_\mathrm{Fermi}$ "is applicable for helium but will need to be amended for carbon and oxygen white dwarfs and cores of AGB stars." In SNEUT this cutoff chooses between the two forms of the bremsstrahlung losses, the weakly degenerate one above $0.01\,T_\mathrm{Fermi}$ and the liquid-metal one with the ¹²C parameters below it; it does not limit the routine, and the parameters are the same for every composition (settled from the code, Nov 9, 2026: sneut.f, lines 882–889 ↗).

How it fits

Who calls it: NEUTRINO.
What it calls: AZBAR and SNEUT.
Outputs: SNU, DSNUDT, DSNUDD. SNEUT also returns the derivatives with respect to $\bar A$ and $\bar Z$ (DSNUDA, DSNUDZ), which are dropped here.

The method

With mass fractions $X_i$, nucleon numbers $A_i$ and charges $Z_i$, the molar abundances $Y_i = X_i/A_i$ give $$\bar A = \frac{1}{\sum_i Y_i},\qquad \bar Z = \bar A \sum_i Z_i\,Y_i .$$

Definitions

subroutineNULOSSES

lines 19–58 · GitHub

Called by NEUTRINO

Flowchart of its calls, in order (2)

AZBAR 46→SNEUT 52

subroutineAZBAR

lines 61–97 · GitHub

The mean nucleon number and charge of the mixture (equations above), from Timmes' code.

Called by NULOSSES

Change log

The changes since rp_1

Changed since rp_1. None: the file is the same as at rp_1.

1c.. 2c.. 3c.. neutrino loss subroutine modified by G. Newsham 4c.. from codes of N. Itoh & F. Timmes 5c.. (9/06) 6c.. 7c.. 8c.. Currently uses just the carbon coefficients for the bremsstrahlung 9c.. neutrino losses (the differences for other elements is slight.) 10c.. We also currently set the fermi temperature cuttoff at 0.01 Tfermi. 11c.. This is applicable for helium but will need to be amended for 12c.. carbon and oxygen white dwarfs and cores of AGB stars. 13c.. 14c.. 15 16 17 18 19 subroutine nulosses(temp,den,snu,xmass,ymass,aion,zion, 20 & & dsnudt,dsnudd) 21 22 23 implicit none 24 save 25 26 27c..tests the neutrino loss rate routine 28 29 30c..ionmax = number of isotopes in the network 31c..xmass = mass fractions 32c..ymass = molar fractions 33c..aion = number of nucleons 34c..zion = number of protons 35 36 37 integer ionmax 38 parameter (ionmax=4) 39 double precision xmass(ionmax),ymass(ionmax), 40 1 1 aion(ionmax),zion(ionmax),temp,den,abar,zbar, 41 2 2 snu,dsnudt,dsnudd,dsnuda,dsnudz 42 43 44 45c..get abar and zbar 46 call azbar(xmass,aion,zion,ionmax, 47 1 1 ymass,abar,zbar) 48 49 50 51c..get the neutrino losses 52 call sneut(temp,den,abar,zbar, 53 1 1 snu,dsnudt,dsnudd,dsnuda,dsnudz) 54 55 56 57 return 58 end 59 60 61 subroutine azbar(xmass,aion,zion,ionmax, 62 1 1 ymass,abar,zbar) 63 implicit none 64 save 65 66 67c..input 68c..mass fractions = xmass(1:ionmax) 69c..number of nucleons = aion(1:ionmax) 70c..charge of nucleus = zion(1:ionmax) 71c..number of isotopes = ionmax 72 73 74c..output: 75c..molar abundances = ymass(1:ionmax), 76c..mean number of nucleons = abar 77c..mean nucleon charge = zbar 78 79 80 81c..declare 82 integer i,ionmax 83 double precision xmass(ionmax),aion(ionmax),zion(ionmax), 84 1 1 ymass(ionmax),abar,zbar,zbarxx,ytot1 85 86 87 zbarxx = 0.0d0 88 ytot1 = 0.0d0 89 do i=1,ionmax 90 ymass(i) = xmass(i)/aion(i) 91 ytot1 = ytot1 + ymass(i) 92 zbarxx = zbarxx + zion(i) * ymass(i) 93 enddo 94 abar = 1.0d0/ytot1 95 zbar = zbarxx * abar 96 return 97 end

1"""Python version of nulosses.f (YREC 7be4133): the neutrino energy-loss 2rate of a mixture, from Timmes' code (Grant Newsham 9/06).""" 3 4import numpy as np 5 6from pyrec.sneut import sneut 7 8# PARAMETER (Fortran lines 37–38). 9IONMAX = 4 10 11 12def nulosses(temp: float, den: float, snu: float, xmass: np.ndarray, ymass: np.ndarray, aion: np.ndarray, 13 zion: np.ndarray, dsnudt: float, dsnudd: float) -> tuple[float, float, float]: 14 """The mean nucleon number and charge of the mixture (azbar), then the 15 neutrino loss rate and its derivatives in T and rho (sneut). 16 17 Translates: nulosses.f#NULOSSES (7be4133) 18 19 Arguments: temp (K) and den (g/cm^3), unlogged; the mass fractions 20 xmass, atomic masses aion and charges zion of the IONMAX species 21 (index 0 unused); ymass, set in place to the molar abundances; snu, 22 dsnudt and dsnudd are passed in with any value. 23 24 Returns (snu, dsnudt, dsnudd). 25 26 """ 27 28 # abar and zbar (Fortran lines 45–47). 29 abar = zbar = 0.0 30 abar, zbar = azbar(xmass, aion, zion, IONMAX, ymass, abar, zbar) 31 32 # The neutrino losses (Fortran lines 51–53); the derivatives in abar 33 # and zbar are dropped. 34 # Question (see the page): the Fermi-temperature cutoff inside sneut. 35 dsnuda = dsnudz = 0.0 36 snu, dsnudt, dsnudd, dsnuda, dsnudz = sneut( 37 temp, den, abar, zbar, snu, dsnudt, dsnudd, dsnuda, dsnudz) 38 return snu, dsnudt, dsnudd 39 40 41def azbar(xmass: np.ndarray, aion: np.ndarray, zion: np.ndarray, ionmax: int, ymass: np.ndarray, abar: float, 42 zbar: float) -> tuple[float, float]: 43 """The mean nucleon number abar = 1/sum(X_i/A_i) and mean charge 44 zbar = abar*sum(Z_i X_i/A_i) of the mixture. 45 46 Translates: nulosses.f#AZBAR (7be4133) 47 48 Arguments: xmass, aion, zion (index 0 unused); ionmax, the number of 49 species; ymass, set in place to X_i/A_i; abar and zbar are passed in 50 with any value. 51 52 Returns (abar, zbar). 53 54 """ 55 56 # Fortran lines 87–95. 57 zbarxx = 0.0 58 ytot1 = 0.0 59 for i in range(1, ionmax + 1): 60 ymass[i] = xmass[i] / aion[i] 61 ytot1 = ytot1 + ymass[i] 62 zbarxx = zbarxx + zion[i] * ymass[i] 63 abar = 1.0 / ytot1 64 zbar = zbarxx * abar 65 return abar, zbar