Astronomy 1

A.Y. 2020/2021
Overall hours
Learning objectives
The goal of this course is to provide the students with a general
overview of stellar physics. Starting from the fundamental properties of
stars as inferred from observation (photometry, spectroscopy, parallax,
mass measurements in binary systems), the features of physical stellar
models are introduced. These include the equations of stellar
equilibrium, energy production, stellar evolution. Along the path, some
of the fundamental physical quantities and concepts of astrophysics are
introduced, which will be a basis for the course Astronomy II and for
other courses in the astrophysics curriculum.
Expected learning outcomes
Students at the end of the course are expected to reach the following
1. to correctly use basic quantities and concepts, such as luminosity
and magnitude (relative and absolute), surface brightness, flux density,
effective temperature, luminosity radius, etc.
2. to describe the main properties of a stellar spectrum, continuous
radiation and absorption lines
3. to calculate relative velocities of astrophysical sources from
Doppler effect measurements, and to evaluate the effects of temperature
and pressure from the shape of absorption line profiles
4. to be able to discuss the main properties of the Sun, its structure,
cycle, magnetic activity, the characteristics of the photosphere,
chromosphere, corona
5. to gain familiarity with the mechanisms of nuclear energy production
in stars, including the information of solar interior from
helioseismology and neutrino physics
6. to gain familiarity with the equations of stellar equilibrium, af the
mechanisms of radiative and convective energy transfer in the interior
of stars
7. to be able to discuss stellar evolution for stars of different mass
ranges, including their final stages
8. to be able to discuss the properties of degenerate gas, the nature of
white dwarfs and neutron stars, the conditions for the formation of a
stellar black hole
9. to be able to calculate astronomical distances from observations of
stellar properties, including measurements of trigonometric parallax,
spectroscopic parallax, measurement of Cepheid variables, Supernovae Type Ia
Course syllabus and organization

Single session

Lesson period
First semester
In case of travel restrictions due to Covid-19, the course will be delivered entirely remotely. In this case, the lectures will be offered in virtual classrooms (zoom platform) in synchronous connection, with the possibility of real-time interaction between the students and the teacher.
Course syllabus
PART I - Fundamental properties of stars
- Historical introduction
- Continous radiation from stars. Brightness. Electromagnetic spectrum. Planck's law. Colour indexes. Stellar distances. Absolute magnitudes.
- Spectral lines in stars. Spectral types. Formation of spectral lines. Hertzsprung-Russell diagram.
- Binary stars and stellar masses. Doppler effect for circular orbits. Binary stars in elliptical orbits. Stellar masses. Stellar sizes.
- The Sun as a typical star. Fundamental structure. Elements of theory of radiative transport. The photosphere. The chromosphere. The solar corona. Solar activity.

PART III - Stellar evolution
- The main sequence. Sources of stellar energy. Nuclear astrophysics: formation of elements in equilibrium and non-equilibrium conditions. Stellar structure. Hydrostatic equilibrium. Radiative and convective energy transport. Cosmic abundances. Stellar models. Solar neutrinos.
- The final phase of stellar evolution. Beyond the main sequence. Giants. Cepheid variables. Planetary nebulae. White dwarves.
- Relativity. Special and general relativity: a short introduction. Astronomical tests for general relativity. Gravitational redshift. Gravitational waves. Schwarzschild radius. Black holes.
- The final phase of massive stars. Supernovae and SN remnants. Neutron stars. Pressure, rotation and magnetic field of compact stars. Pulsars. Pulsars and interstellar space. Stellar black holes.
- Evolution of compact binaries. Compact systems with a white dwarf. Compact systems with neutron stars. Systems with a black hole. Examples of compact systems.
Prerequisites for admission
The student is assumed to be familiar with the basic knowledge from the Laurea Triennale in Physics.
Teaching methods
During the lectures, students are invited to ask questions and contribute comments, to facilitate their critical and personal comprehension. Multi-media tools are regularly used, and made available to the students after each lecture.
Teaching Resources
-- Marc L. Kutner, "Astronomy: a Physical Perspective", Cambridge Univesity Press, 2003
-- D. Maoz, "Astrophysics in a nutshell", 2008, Princeton University Press
Furthermore, papers, materials, slides used during the lectures will be made available to the students.
Assessment methods and Criteria
A detailed discussion about some of the topics of the course, testing the critical understanding of the contents.
FIS/05 - ASTRONOMY AND ASTROPHYSICS - University credits: 6
Lessons: 42 hours
Ask the teacher
Laboratorio di Strumentazione Spaziale, Department of physics (via Celoria 16, Milano)