Lecture 31 – Star Formation and Evolution, Part 3/3: Massive Stars and Stellar Explosions
Summary / Checklist of the Main Concepts to Understand and Remember

Evolution of High-Mass Stars  
• Stars more massive than 8-10 solar masses end their lives in a very different way from lower-mass stars.  
• They live shorter main-sequence lives, because they burn hydrogen and produce energy at a much higher rate.  
• After the main sequence, the first stages are similar to those of lower-mass stars, but they become larger giants.  
• Eventually, however, their cores reach high enough temperatures for new nuclear fusion reactions to produce heavier elements, up to iron (Fe).  
• End: When the core is mostly iron and cannot burn anymore fusion stops, the core contracts, the star collapses and explodes.  
     
Supernova Explosions  
red bullet What is a supernova? How would a supernova appear in the sky if it happened in our part of the galaxy?  
red bullet What are the two types of supernovas? How do core-collapse (type II) and white-dwarf (type Ia) supernovas happen?  
• [Why are type Ia supernovas very useful for astronomers?]  
• What is the maximum mass a white dwarf can have? Why is there a maximum, and what happens if the mass becomes larger?  
red bullet How often on average do we expect to see a supernova in our galaxy? When was the last one seen in our galaxy?  
red bullet What is left of the star after a supernova explosion? (In each of the two cases of core-collapse and white-dwarf supernovas.)  
• What do we see with telescopes at the location where a supernova exploded in the past?  
     
     

Topics from the lecture page and textbook not listed above [or between square brackets] were not covered in class;
Underlined words indicate that I will expect students to remember a number or a name related to that topic.

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