Syllabus
* Theory of stellar atmospheres
Characterising radiation fields: specific intensity, flux, energy density, Maxwell equations, radiation pressure tensor, opacity, emissivity, optical depth, scattering, photon mean free path.
Radiative transfer equation: formulation, moments, diffusion approximation, boundary conditions, formal solution, numerical solutions - Feautrier method, short characteristic method, long characteristic method, discontinuous finite element method, Monte Carlo method. Radiative transfer equation in moving media - Lorentz transformation, radiative transfer equation in the observer frame, in the comoving frame, Sobolev method.
Grey atmosphere, Rosseland mean opacity, Planck mean opacity, Milne relations, Eddington solution.
Einstein coefficients, Planck law, Einstein relations, classical oscillator, cross sections, oscillator strengths, Gaunt factors, opacity, negative ion of hydrogen, electron scattering, Rayleigh scattering, Boltzmann equation, Saha equation, state equation, thermodynamic equilibrium, local thermodynamic equilibrium, non-LTE, radiative rates, collisional rates, equation of statistical equilibrium.
Models of stellar atmospheres
Line broadening - natural broadening, pressure broadening, thermal broadening, Voigt function, Holtzmark theory, Milne-Eddington model, limb darkening, gravity darkening.
* Physical processes in individual objects
Physical processes in stellar atmospheres: convection - convective equilibrium, semi-convection, thermohaline convection; pulsations; element segregation - diffusion equation, settling, radiative levitation; stellar winds - isothermal winds, non-isothermal winds, coronal winds (see solar physics), dust driven winds, line driven winds, Alfvén wave driven winds (see solar physics).
Planetary atmospheres and atmospheres of brown dwarfs: terminology astronomy vs meteorology, processes in planetary atmospheres, types of giant planets, standard model, numerical models.
Atmospheres of individual stellar types: pre-main sequence stars, main sequence stars, WR stars, white dwarfs, neutron stars, accretion discs, novae.
Annotation
Introduction to modeling of stellar and planetary atmospheres; radiative transfer equation and its numerical solutions; models of atmospheres, magnetohydrodynamics and equilibrium in atmospheres; physical processes in atmospheres of different stellar types, planets and accretion discs. Two-level model of atom, numerical solution of the radiation transfer equation.