How were the elements from iron to uranium made?
Nuclear Astrophysics is the research field which explains the origin of the elements and the source of much of the energy in the universe. We know that chemical or biological processes can not convert an atom from one element to another. Only nuclear reactions or radioactive decays can change the charge and mass of an atomic nucleus and therefore convert between elements. The relative abundance of the elements and isotopes we find in nature therefore represents a signature of the nuclear processes and a record of their history from the beginning of the universe until today. We know that Hydrogen was formed shortly after the big bang and that nuclear processes fused some of this Hydrogen into Helium and Lithium about 3 minutes after the big bang. However, big bang nucleosynthesis could not proceed farther because there are no stable nuclei with an atomic mass of 5 or 8. When Hydrogen condensed and formed stars, it ignited in thermo-nuclear fusion reactions which produce most of the ener
