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PURE FUNCTION He_ioniz(nHe,ne,T)

Defined in

contrib/astro/physics/cool/cool.f90

Inputs

• nHe (=1.d0) (in cm^-3)
• ne (=1.d0) (in cm^-3)
• T (in K)

Description

• If T ⇐ 1000 K, He_ioniz = 0. Otherwise:
• Calculates rates for the direct (collisional) ionization of He using the expression of Arnaud & Rothenflug (1985A&AS..60..425A):
  • He_ioniz = nHe*ne * (const*(exp(-x)/x)*F/((kT)^1.5)), where
    • x = I_He/kT (I_He = 24.6 eV)
    • F = A*(1-x*f1) + B*(1+x-x*(2+x)*f1) + C*f1 + D*x*f2, and A,B,C,D are constants
    • f1 = exp(x) * de1(x), where de1 is an exponential integral function, = integral(1 → inf) of (e^-tx/t)dt, from slatec library.
    • f2 = exp(x) * [integral(1 → inf) of (e^-tx*ln(t)/t)dt], calculated in FUNCTION df2
• Values are nominally in cm^-3 s^-1, however:
  • When used in initneqCool, nHe & ne are inputed as 1.d0.
  • The actual densities aren't multiplied in until the tables are used in i_evolove.f90 to calculate the actual cooling rates.
• Is used in Subroutine initneqCool (in cool.f90) to build table of cooling values for this process

Called in

contrib/astro/physics/cool/cool.f90, in SUBROUTINE initneqCool

Functions Used

• de1 (as defined above, from slatec library)
• df2 in contrib/astro/physics/cool/cool.f90

Modules Used

None