AST 553 Stellar Interiors

Credit Hours: 4
Prerequisite: AST 461, AST 462 or AST 453

Quantitative theory of model integration and description of early stages of evolution. Variable stars and rotational models. Later stages of evolution, white dwarfs, neutron stars, nucleosynthesis, supernova models.

syllabus

1. Introduction. Observational properties of stars; stellar populations; Hertzsprung-Russell diagram; nucleosynthesis and chemical evolution; time scales: dynamical, Kelvin -Helmholtz, nuclear.
2. Hydrostatic equilibrium. Equation of continuity; Poisson's equation; the momentum equation; hydrostatic equilibrium; isothermal sphere, atmosphere and disk; polytropes; Lane-Emden equation; analytic solutions; mass-radius relations; Virial tTheorem; equation of state; thermal equilibrium; pressure; internal energy; gas pressure; radiation pressure; Eddington models.
3. Degeneracy. Degeneracy; pressure; transition to degeneracy; contraction without burning; Chandrasekhar mass; mass-radius relation for zero temperature stars.
4. Energy transport. Energy equation; radiative transport; convective instability; efficiency of convection; adiabatic temperature gradient; stellar atmospheres; the Eddington approximation; Eddington luminosity.
5. Opacity. Free electron scattering; free-free opacity; bound-bound opacity; bound-free opacity; H- opacity; total opacity; conductive opacity.
6. Nuclear burning. Fusion; binding energy; Coulomb barrier; tunneling; cross-sections; reaction rates and the Gamow peak; electron shielding; rates; p-p chains, CNO bi-cycle, triple-alpha reaction.
7. Stellar structure overview. Equations of stellar structure; steady equations; boundary conditions; fitting point; Newton-Raphson technique; stability and uniqueness of solutions; luminosity-mass-radius relations; structure of stars-overview.
8. Star formation. Star formation; collapse of molecular cores; Jeans mass; the angular momentum problem; magnetic fields; flux-freezing; magnetic flux problem.
9. Stellar evolution. Stability on the main-sequence; Hayashi limit; overview of evolution; formation of helium core; Schönberg-Chandrasekhar limit; core collapse; red giant phase; evolution to asymptotic giant branch; shell burning; He flash; shell flashes; asymptotic giant branch; thermal pulses (single shell); thermal pulses (two shells); instability strip; pulsations; supernovae: end states for low mass, intermediate mass, and high mass; stars; type Ia, Ib, Ic and II supernovae; detonation and deflagration fronts; envelope ejection.

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