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 capabilities: 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
Lesson period: First semester
(In case of multiple editions, please check the period, as it may vary)
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.
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.
-- 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.