Lecture 10 - Radiative Transfer (2/16/99)

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ASTR012 Reading:
Chapter 8-7, 10-2, 13-1 (ZG4)

pages 38 - 42

This is an X-ray image of the Sun obtained on February 21, 1994. The brighter regions are sources of increased X-ray emissions. (Courtesy Calvin J. Hamilton, and Yohkoh)
? Key Question: How does an atmosphere attenuate a beam of light?
! Key Principle: Radiative Transfer
# Key Problem: Construct a Model Photosphere


  1. Radiative Transfer II - Opacity and Optical Depth
  2. The Plane-Parallel Atmosphere
  3. Radiative Transfer III - Emission + Absorption
  4. Opacity in the Solar Photosphere
  5. Interlude - Iterative Solution of Equations

Iterative Solution of Numerical Problems

I mentioned in class that a wide range of numerical problems can be solved iteratively, often with just your calculator. These problems are of the type that can be put in the form

x = f(x)

and that starting with a guess x_1 you can iterate

xi+1 = f( xi )

to arrive at a stable solution. Note that there are often 2 or more ways to set up the equation, since by taking the inverse x = f-1(x) should work also (that isnt an exponent, but a functional inverse).

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smyers@nrao.edu Steven T. Myers