Structure and Evolution of Stars

Table of Contents


In this Lecture (PHY421F), we wish to explain the so-called Hertzsprung-Russell diagram. Stellar physics is a central research area because stellar feedback is essential to understand the evolution of galaxies in the Universe. Furthermore, the first stars which formed presumably at a redshift of ~10-20 provided the Universe with the first metals giving birth to the Universe as we see it.

The ESO/Gaia mission is currently building the most extended and accurate HR diagram for billions of stars, providing new insights in our understanding of the evolution of the universe. On the other hand, the increasing sensitivity of telescopes (ALMA, soon-coming NASA/JWST) allows observations of star formation and evolution at high redshift when the first galaxies formed in the Universe, widening considerably the scope of our knowledge on the structure and evolution of stars.

In this lecture, we will explore the physical processes that drive the formation, evolution, and death of stars. Although some of these processes will be investigated in quite some depth, approximations must be used because the many, coupled, physical processes would otherwise require involved numerical simulations. In a first part, we will establish the set of ordinary differential equations that describe the physical and chemical state of a star. We will then use these equations to elucidate the remarkable features of the Hertzsprung-Russell diagram.

The lectures are in french, but all slides, problems, articles, references, etc… are in English.

Outline and Slides

Chapter Title Slides HTML Slides PDF Notes  
  Stellar structure and evolution I        
1. Introduction here      
2. Observations of stellar formation and evolution here      
3. Overview of stellar evolution here      
  Basic Equations        
4. (1) Mass and momentum conservation     here  
5. (2) Energy conservation     here  
6. (3) Energy transport     here  
  Gas characteristic equations        
7. (1) Equations of state of stellar matter here   here 12/03
8. (2) Opacity here     19/03
9. (3) Nuclear energy production here   here 19/03-02/04
  Stellar Evolution II        
10. Overview and main-sequence models here   here 08/04
11. Post-main sequence evolution here here   15/04
  Useful constants here      
x. Chemical evolution     here  
x. Star formation here   here  
x. Pre-main sequence stars here      
x. Homologous models of main sequence stars here   here  
x. Evolution - Overview here      
x. Post-main sequence stars here   still in progress  


Supplementary Material

  • The ESA/GAIA mission
  • Variable stars: a spectacular movie based on the ESA/Gaia DR2; in this movie, you will see Cepheids and lon period variables in the HR diagram;


  • Stellar Structure and Evolution, Kippenhahn, Weigert, and Weiss, Springer
  • Steven Stahler and Francesco Palla, The Formation of Stars, 2004, Wiley
  • Martin Harwit, Astrophysical concepts (A&A library, Springer)
  • Hansen and Kawaler, Stellar interiors – Physical principles, structure, and evolution (A&A library, Springer)
  • Ward-Thompson and Withworth, An introduction to star formation, Cambridge University Press
  • Astrophysics I and II, Bowers and Deeming, Jones and Bartlett Publishers, Inc.