Stellar interiors: hydrostatic equilibrium, equation of state, opacity, Rosseland mean, thermonuclear reactions, convection, mixing length. The standard solar model, neutrino astrophysics, solar oscillations. Stellar atmospeheres. radiative transfer, the grey atmosphere. Saha-Boltzmann equations Masses of celestial objects: Eddington limit, Chandrasekhar mass, minimum mass of a star, mass of planets. Roche lobes, accretion disks. Tidal forces.
E. Landi Degl'Innocenti, "Fisica Solare", Springer Italia.
E. Landi Degl'Innocenti, "Spettroscopia Atomica e Processi Radiativi", Springer Italia.
Notes of the lectures on the arguments not covered in the mentioned books are available.
Learning Objectives
Fundamental knowledge in non-relativistic astrophysics,. Basic competences of the physicist relatively to astrophysics. Skills in working out physical models of astrophysical objects and verifying their validity, in guessing structural analogies among different phenomenological scenarios.
Prerequisites
Recommmended courses: all courses of the "Corso di Laurea" in Physics and Astrophysics.
Teaching Methods
9 CFU, 80 hours of lecturing, including 15 hours of exercises.
Further information
Students can consult the teacher on Tuesdays from 16:30 to 17:30 (after the lecture).
Type of Assessment
Oral test
Course program
Stellar interiors: hydrostatic equilibrium, fundamental equation of the stellar structure, polytropic stars ,Lane-Emden equation and its consequences, equation of state for the stellar plasma, mean molecular weight, fundamental concepts of plasma physics, plasma frequency, Debye length, example of the terrestrial ionosphere. Corrections to the equation of state due to electrostatic interactions and to degeneracy, thermonuclear reactions in stellar interiors, p-p and CNO cycles, nuclear rates according to the Gamow model, tunnel effect in WKB approximation. Radiative equilibrium, solution of the transfer equation in the diffusion approximation, opacity, Rosseland mean, Thomson scattering, free-free and bound-free transitions, Kramers equations. Convection, Schwarzschild criterion for stability against convection, adiabatic gradient, Brunt-Väisälä frequency, corrections to the adiabatic gradient due to ionization, mixing length theory, kinetic equations for chemical abundances. The standard solar model, neutrino astrophysics, Davis experiment, non-standard solar models, further experiments of neutrino capture, neutrino oscillations, solar oscillations, waves in a stratified medium in Cowling approximation, p-modes and g-modes. Fundamental properties of the solar spectrum, classification of main-sequence spectral types, interpretation of stellar spectra. Boltzmann factor and Saha factor. Theory of stellar atmospheres, radiative transfer, optical depth, Eddington-Barbier approximation and its consequences, the grey atmosphere in Eddington approximation, limb darkening, empirical modles of stelar atmospheres. Absorption coefficient in stellar atmospheres, classical theory of Thomson and Rayleigh scattering, and of atomic absorption in spectral lines, damping, Doppler effect, Voigt function, line formation, (Mlne-Eddington model), saturation.
Equation of stete for a degenerete gas of electrons, polytropic model of a degenerate star, Chandrasekhar mass, typical radius of degenerate stars. Pulsars and their properties, model of the rotating dipole for neutron stars, age, magnetic field, and magetosphere of pulsars. Simplified three-bodies problem, Roche lobes and Lagrangian points, their stability. Tidal forces, effects of sun and moon on the earth. Keplerian disks, angular momentum loss due to viscosity, luminosity of a Keplerian disk, detailed model, turbolent viscosity. Mass-luminosity relation for main-sequence stars, Eddington limit, minimum mass of a star. Rigidity of condensed matter, elementary model of elasticity, tensile load, mass of planets. Theory of spectroscopic binaries, observation of extra-solar planets.