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Rosseland Mean Opacity

(Rosseland Mean)
(a useful weighted average of opacities at all the wavelengths)

The Rosseland Mean Opacity (or simply Rosseland Mean) is a weighted average of the Opacity of a material, e.g., gas or Plasma through which Electromagnetic Radiation is passing. It is designed to be useful for models that try to do a single calculation covering all Wavelengths rather than treating each wavelength individually, and given the complexity of the effect of a gas on a spectrum, to make such models tractable. It is:

 1    1  ∞ Iν
——— = — ∫   —— dν
<κ>   I 0   κν


A model Stellar Atmosphere using this short cut is called a Gray Atmosphere.


Referenced by:
Gray Atmosphere
Mean Molecular Weight (μ)
Equation of Radiative Transfer (RTE)