Stellar Astrophysics

course ID





14 Weeks

Semester DD


Course details

1. Stellar Structures: empirical scenario
1.1 Galactic spheroid
1.2 Stellar Populations
1.3 Stellar systems
1.4 Metallicity distributions
1.5 Kinematic properties
2. Stellar Structures: theoretical framework
2.1 Momentum conservation
2.2 Mass conservation
2.3 Radiative and conductive transport equations
2.4 convective trasport equation: Schwarzschild and Ledoux criteria
2.5 Mixing length theory
2.6 Energy Conservation
2.7 Stellar envelopes and atmospheres
3. Physical conditions in stellar interiors
3.1 Equation of state
3.2 Radiative and molecular opacities
3.3 Energy generation
3.4 Nuclear reactions
4. Solutions of the equations for stellar interiors
4.1 Analytical solutions
4.2 Virial theorem and electron degeneracy
4.3 Initial conditions and boundary conditions
4.4 Saha equation and evolution of chemical elements
5. Star formation
5.1 Jeans mass and star formation
5.2 Strutture stellari completamente convettive: Hayashi track
5.3 Approch to the central hydrogen burning phase
6. Hydrogen burning phases
6.1 The p-p chain
6.2 The bi-cycle CN-NO
6.3 The Main Sequence (MS) in low-, intermediate- and massive stars
6.4 Standard solar model
6.5 The Mass-Luminosity relation
6.6 The Schoӧnberg-Chandrasekhar limit
6.7 The sub giant branch and the red giant branch (RGB)
6.8 The RGB bump
6.9 The Tip of the RGB and the central Helium flash
7. Helium burning phases
7.1 Nuclear reactions
7.2 The Zero Age Horizonthal Branch (ZAHB)
7.3 Central Helium burning phase in low-, intermediate- and massive stars
8. Advansed evolutionary phases
8.1 Asymptotic giant Branch (AGB)
8.2 Chandrasekhar limit
8.3 Carbon/Oxygen and helium core white dwarfs
8.4 Advansed evolutionary phases in massive stars: Supernovae
9. Stellar observables of cosmological interest
9.1 Primordial helium content
9.2 Absolute and relative ages of globular clusters
9.3 The Cepheid instability strip
9.3 Primary and secondary distance indicators
9.4 The Hubble constant


The master is aimed at providing an advanced preparation on Physics, with a detailed knowledge of the key topics in the recent research in Astrophysics. The learning outcomes rely on a detailed knowledge of quantum mechanics and solid state physics. The main objective of the course in Stellar Astrophysics is to provide to the student the knowledge of the basic physics required to understand the formation and evolution of stellar structures. This knowledge is fundamental to understand not only the evolution of the baryonic content of the Universe, but also to trace its chemical evolution. These concepts are a stepping stone not only for the students interested in understanding the local Universe, but also for those interested in the large scale structure of the Universe in cosmological models and in compact objects (stellar mass black holes, neutron stars, white dwarfs).

The student at the end of the semester will acquire a detailed knowledge on the energy
conservation equations (momentum, mass, energy) of stellar interiors and of the trasnport
equation (radiation, conduction, convection). Moreover, the student will acquire solid
knowledge on micro (equation of state, opacity, electron degeneracy, nuclear reactions)
and macro (rotation, mass loss, convective transport, chemical evolution) physics driving
the formation and the evolution of stellar structures. This knowledge will allow the students
to fully understand the hydrogen-, helium-burning and advanced evolutionary phases for low-, intermediate- and massive stars. The sudent will be able to fully exploit the fundamental plane for stars (Hertzsprung Russell diagram) to trace the different evolutionary phases and its use to understand resolved stellar populations.

The student at the end of the semester will acquire the knowledge of stellar evolution physics to attack and solve a broad range of stellar astrophysical problems. To be more specific, the student will be able to estimate the absolute and relative age of globular clusters, to estimate the chemical abundances (primordial helium, metallicity) and to measure cosmic distances by using primary distance indicators. Moreover, the student will have a detailed knowledge of the impact that intrinsic and systematic errors affect the estimate of astrophysical and cosmological parameters.

The students will take an oral exam aimed at verify the knowledge of stellar evolution
physics together with a written report concerning a specific project. The written report
can be done either individually or in small groups. To undertake the project, the students
are requested to perform several critical choices concerning the empirical data (Gaia,
Hubble Space Telescope, ground based telescopes) and the theoretical predictions
(stellar isochrones, luminosity functions, synthetic color-mgnitude diagrams) available
on the web. Moreover, the students, in dealing with the comparison between theory and
observations, will acquire a substantial critical judgement concerning empirical and
theoretical uncertainties affecting the estimate of astrophysical/cosmological parameters
and in turn, on the strategic and methodological choices to undertake the project.

The student is requested to take an oral exam to verify the knowledge acquired on the
basic physics of stellar interiors. This requires a relevant effort to summarize the
entire programm and to link the two main moduls of the course (basic physics for
stellar interiors, application to the different evolutionary phases). The student
is also requested to submit, before the exam, a written report on a specific project.

The student during the course will acquire the knowledge required to build up a
research activity in stellar Astrophysics (resolved stellar populations) and/or
on the large scale structure of the Universe (un-resolved stellar populations)
and/or in the estimate of astrophysical/cosmological parameters. This means unique
opportunities not only for a PhD, but also job opportunities concerning space
activity and big data.