I've been reading lately about the origin of the elements and their production in stars and I have a few questions. Let's start by the simple stuff, and correct me if I'm wrong. When stars form and join the main-sequence they burn hydrogen to make helium. At a certain stage when the hydrogen in the core is exhausted, depends on their mass, they turn into red giants and begin burning helium and make the heavier elements by carbon burning, neon burning, silicon burning. Elements up to iron can be produced like that. If the star is massive enough, it will end its life in a supernova and form heavier (actinids, etc) elements in the r-process. So far so good? I hope so. I've also read that certain stars can make elements up to Bi by the s-process. Is this occurring in a supernova? If not, then why is it widely cited that Fe is the heaviest element to form in stars when in fact heavier up-tp-Bi elements can form? Thanks for clearing up my confusion.