Astronomy 631:
Radiative Transfer and Stellar Atmospheres

Radiation field: Definitions, energy density, radiation pressure.
Equation of transfer: Interaction of radiation and matter, transfer equation, angular moments, radiative equilibrium, diffusion approximation.
Grey atmosphere problem: Definition, mean opacities. approximate solutions.
LTE equation of state.
Absorption cross section: Einstein coefficients, continuous absorption and scattering processes.
Solution of the transfer equation.
LTE model atmosphere: Assumptions, boundary value problem.
Statistical equilibrium: Requirements for LTE, non-LTE rate equations.
Non-LTE model atmosphere for early-type stars.
Line formation: Observable quantities, line profiles, Voigt function.
Classical treatment of line formation: Milne-Eddington model, curve of growth, LTE spectrum synthesis.
Non-LTE line formation: Two level atom with and without continuum, multilevel atoms.
Radiative transfer with macroscopic velocity fields: Modified transfer equation with velocity fields, co-moving frame approach, Sobolev approximation, escape probabilities, and non-LTE.
Stellar winds: Hydrodynamic equations of radiation-driven winds, line and continuum radiative forces, critical points and singularities, analytical and numerical solutions.

This outline is representative only, and is likely to change from instructor to instructor and from year to year.