ASTROPHYSICS

This course is devoted to give a fairly deep panoramic view of the phenomena occurring in our Universe.

Particular attention will be given to the quantitative description of the physical mechanisms that explain the occurrence of such phenomena.

Due to the intrinsic interdisciplinary nature of Astrophysics, when necessary, some concepts will be introduced in heuristic way; such consepts will be treated in depth subsequently in other courses.

The approach used during the course will be both observalional and theoretical.

The structure of the course consists in lectures addressed in the classroom.

It is programmed to perform one or more visits of the students to the Station the Stellar Stations of the Catania Astrophysical Observatory.

Should umpredictable circumstances require online or blended teaching, appropriate modifications might be introduced to what is hereby stated, in order to achieve in any case the main objectives of the course.

Exams might take place on line, depending on circumstances.

1 – Introduction

Metodology of scientific investigation in Astrophysics – Distance ladder and units – Instrumentation – Astronomical coordinates.

 

2 – The stars

Fundamental quantities (mass, radius and luminosity) - Magnitudes – Spectral classification of stars – The Hertzprung-Russell diagram - Luminosity class.

– Stellar Atmospheres

Radiation transport – Model atmospheres – Limb darkening - Line formation – Boltzmann and Saha equations* – Einstein's coefficients – Mechanisms of line widening – Abundance analysis.

– Internal Structure

Equations of the internal structure of stars – Mass-Luminosity relation – Nuclear Fusion – Energy transport – Schwarzschild's criterion for convection.

– Stellar Evolution

The Virial theorem* - The Jeans criterion for gravitational collapse and star formation - Pre- and post-main sequence stellar evolution – Degenerate Fermi gas* - Final phases of stellar evolution: white dwarfs, neutron stars and black holes - Pulsating varable stars.

 

3 – The Sun: a main sequence star

Atmosphere: photosphere, cromosphere, corona – Convection zone – Differential rotation – Alfvèn's theorem* - Dynamo action for the generation of magnetic fields – Buoyancy of magnetic flux tubes and solar activity (sunspots, facolae, prominences, flares) - The neutrino problem.

 

4 – The interstellar medium

Diffuse and dense interstellar clouds and the intercloud medium – Gas and dust – Cooling and heating mechanisms of clouds - H II regions - Chemistry in the gas phase and on the surface of dust grains.

 

5 – Our Galaxy

Morfology and dynamics – Globular and open clusters – Stellar populations – Dark matter - The supermassive Black Hole – Cosmic rays.

 

6 – External galaxies

Hubble's morphological classification – Physical properties and formation processes of elliptical and disk galaxies – Cluster and supercluster of galaxies – Quasars and the other Active Galactic Nuclei (AGN) - Extragalactic evidences of dark matter.

 

7 – Cosmology

Fundamental observational evidences: Hubble's Law of the espanding Universe, the Cosmic Background – Cosmologic principle - Newtonian Cosmology - Friedmann's equation - Fluid equation – Inflation and primordial fluctuations – Radiation dominated, matter dominated and vacuum dominated Universe – Cosmological models - Dark energy - The cosmological constant - Large and small scale anisotropies of the Cosmic Microwave Background - Thermal history of the Universe.

 

N.B.: The detailed quantitative description of subjects marked with * may be omitted.

G.B. Rybicki & A.P. Lightman: Radiative processes in Astrophysics, Wiley-VCH, New York (2004)

H. Karttunen et al.: Fundamental Astronomy, 5^th ed, Springer Verlag, Berlin (2007)

B.W. Carroll & D.A. Ostlie: An Introduction to Modern Astrophysics 2nd ed, Cambridge University Press, Cambridge (2007)