Course Number: 92023

Course Title: Astrophysics

The course covers both semesters: 2 lectures/week (2 hrs. each)
Lecturer: F. Reale (Associate Prof.)

Prerequisites:
All the courses of the first two years, Astronomy, Structure of matter,
Quantum Mechanics.

Contents:
radiative transfer and stellar atmospheres, detailed studies of the
solar chromosphere and corona, optically thin astrophysical sources,
plasma physics.

Syllabus:

Fundamental of Electromagnetism, radiative transfer, black body
spectrum.

Semi-classical theory of line absorption, Rayleigh-Jeans and Planck
formulations, quantum theory of line absorption, line shapes and line
broadening.

Radiative transfer in stellar atmospheres, source function, growth
curve, convective energy transport in a stellar atmosphere,
Schuster-Schwarzschild model, Milne-Eddington model.

Continuous absorption coefficient: contribution from the neutral and
negatively ionized hydrogen, from negative helium and from the heavier
elements.

Models of stellar photospheres: temperature distribution and
hydrostatic conditions, geometrical depth scale, computation of the
spectrum; effects of the temperature, of the pressure and of the
chemical abundance.

The line absorption coefficient: natural absorption, pressure
broadening, thermal broadening, microturbulence and other broadening
mechanisms, combining absorption coefficients.

Behaviour of spectral lines: behaviour of the line strength, effects of
temperature, pressure and element abundance.

Stellar chemical analysis: scaling laws, curves of growth,
differential analysis and derivation of the abundances.

Primordial elements abundance in the solar system, elements abundance
in stars and nebulae, non-equilibrium conditions.

Solar Chromosphere, small scale and large scale structures, role of
magnetic fields, dynamics of chromosphere.

Solar corona, coronal structuring in closed magnetic loops and open
magnetic structures, scaling laws, diagnostics of coronal temperature
and density, flares.

Optically thin astrophysical X-ray sources, their spectroscopy and
diagnostics.

Fundamentals of plasma physics. Klimontovisch and Vlasov equations,
orbit theory, waves in a plasma, MHD.

Recommended texts:

- G.B. Rybicki e A. P. Lightman, Radiative Processes in Astrophysics ,
New York 1979 (Wiley).
- David F. Gray, The Observation and Analysis of Stellar Photospheres,
New York 1992 (Cambridge University Press)
- C.R. Cowley, The Theory of Stellar Spectra , New York 1970 (Gordon
and Breach).
- A. Dalgarno e D. Layzer (eds.), Spectroscopy of Astrophysical
Plasmas , Cambridge 1987 (Cambridge University Press).
- F.F. Chen, Introduction to Plasma Physics and Controlled Fusion (Vol. 1,
Plasma Physics), New York 1984 (Plenum Press).
- Pallavicini, R., "Spectroscopic Diagnostics of Astrophysical Plasmas"
in
Plasma Astrophysics, C. Chiuderi and G. Einaudi eds., 1996 Springer Verlag

Assessment is by oral examination about the subjects of the course and
about a specific detailed problem assigned to the student at the end of
the course.