origins
- Universe expands
- Gravitational instabilities form galaxies
- ~ 1 billion years after big bang
- Universe is 10-15 billion years old
- Very soon, stars form
- Fusion reactions in center form heavier elements
- i.e. C, N, O, Ca, Na, etc.
- Red Giant stars spew these elements and pollute the interstellar medium
- New stars (2nd generation) like Sun form out of the enriched material
- Supernovae (stellar collapse and explosion)
- also form heavier elements, such as Fe and Iodine, which enriches the interstellar medium
- The Sun formed out of this enriched material