Department of Physics

18904 Stellar Structure and Nucleosynthesis

Course Webpage: https://eclass.uoa.gr/courses/PHYS222

Course Content

• Thermodynamic state of the stellar interior: Equation of state. Mechanical pressure of a perfect gas (perfect monoatomic non-degenerate gas). Electron degeneracy, complete degeneracy-non relativistic case, complete degeneracy- relativistic case, partial degeneracy. Radiation pressure. Quasistatic changes of the equation of state. The ionized real gas. Polytropes. 
• Energy transport in the stellar interior: Energy balance. Radiative transfer. Opacity of stellar matter. Conduction. Convective instability. Neutrino emission. 
• Thermonuclear reaction rates: Kinematics and energetics. Cross section and reaction rate. Non-resonant reaction rates. Nuclear states – shell model. Penetration factors. Maximum cross sections and resonant reactions. Resonant reaction rates in stars. Electron shielding. 
• Major nuclear burning stages: The proton-proton reaction (pp). PPI, PPII, PPIII chains, CNO cycle. Helium burning – triple alpha reaction – nucleosynthesis during helium burning. Advanced burning stages. Photodisintegration.
• Calculation of stellar structure: Boundary conditions. Mass as the independent variable. Composition changes. Numerical techniques. Contraction to the main sequence. The main sequence. Advanced stellar evolution (giant and horizontal branch stages). Rotation. Mass loss. Pulsation.
• Synthesis of the heavy elements: Photodisintegration, rearrangement and silicon burning. Nuclear statistical equilibrium and the e-process. Nucleosynthesis of heavy elements by neutron capture. Cross sections. The s-process. The r-process.