Mother lode
Fusion reactions are much more varied and complicated than outlined above, but the general idea holds. Light elements lead through fusion to the creation of previously non existent heavier elements. Though some elements in the Periodic Table are not created this way but in other exotic reactions, all are the result of synthesis in the core or surroundings of stars. The Sun itself is currently turning hydrogen into helium, and will continue to do so for billions of years. The Sun by the way, will end its days peacefully shedding most of its mass in an outflow of gas while going through red giant and latter white dwarf stages.
Other stars, the ones over 40% heavier than the Sun or more, do not fare so peacefully. The live fast, die young and leave behind a stupendous show. They synthesize more and heavier elements in different phases, until reaching an energy wall. Iron, the last element created by fusion does not yield to pressure and burn into heavier elements. When most of the available lighter fuel has been depleted, the star cannot hold anymore a delicate balance of infalling matter braked by outflowing radiation, and pressure in the iron core rapidly builds up squeezing to the point no further room is left. Then the core rebounds forcefully and in the process the star is torn apart in one of the most colossal of fireworks, a supernova.
Seeding the Universe
The supernova taxonomy includes other processes apart from the one described, but the essence is during the lifetime of a star, non previously existent elements are synthesized from simpler ones. If the star is doomed by size to become supernova and finally explodes, it disperses most of its mass away at enormous speeds, to populate the surroundings with freshly mint matter.
All carbon, oxygen, zinc, calcium, you name it, of what we ourselves are composed, was in a remote time created within one of those furnaces. In fact, chances are we went through this process more than once, for matter expelled from a supernova has a high chance of finding its way to contribute to the birth of another star. If it in turn goes supernova, there we go again.
Second and third generation stars are recognized for the presence of heavy elements that could not possibly have been synthesized there, betraying its pedigree from a previous generation.
Thousands and millions of supernovas explode each year in the
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