src.Atomic.Opacity.HIRayleigh_CrossSection

src.Atomic.Opacity.HIRayleigh_CrossSection(wl)[source]

return Rayleigh scattering cross section of a HI atom in unit of e-26 cm^2

Parameters

wl (wavelength, [\(A\)]) –

Notes

from 1, 2.

HI Rayleigh opacity in LTE is

khray = n_HI * HIRayleigh_CrossSection(wl) * 1.e-26 (/cm)

  • n_HI: hydrogen number density in cm^(-3)

  • stimulated emission is corrected

  • partition function of HI is assumed to be 2.0, which is valid for T < 2.e4 K

modification history:

  • k.ichimoto 18 jun. 1987, 6 Jan. 1992

  • k.ichimoto 19 Feb.1994

  • 2019.9.10 K.Ichimoto from IDL avray.pro

References

1

Gingerich SAO special report 167,21,1964.

2

porinomial fitting for f-f gaunt factor is taken from Carbon & Gingerich (1969) “theory and observation of normal stellar atmosphere” MIT press