In all stars, the main source of energy is nuclear fusion. There are many different types of nuclear fusion.
The nuclear fusion process that converts hydrogen to helium in stars that have about the same core temperature and mass of the sun is called the proton-proton chain. Two protons fuse together, and H is converted to He.
In supernovae, the r-process takes place and creates heavier elements. It involves rapid neutron captures which take seconds. Neutron capture is the process in which the nuclei of an atom fuses with one or multiple neutrons to form heavier elements.
The s-process, which occurs in mostly asymptotic giant branch stars, creates heavier elements, and involves slow neutron captures which takes thousands of years.
The carbon cycle takes place in massive stars around 1.5 times bigger than the sun. A proton is added to carbon, which becomes nitrogen, which in turn becomes oxygen when an additional proton is added. Oxygen then radioactively decays and formed helium and carbon, and the process repeats.
The nuclear fusion process that converts hydrogen to helium in stars that have about the same core temperature and mass of the sun is called the proton-proton chain. Two protons fuse together, and H is converted to He.
In supernovae, the r-process takes place and creates heavier elements. It involves rapid neutron captures which take seconds. Neutron capture is the process in which the nuclei of an atom fuses with one or multiple neutrons to form heavier elements.
The s-process, which occurs in mostly asymptotic giant branch stars, creates heavier elements, and involves slow neutron captures which takes thousands of years.
The carbon cycle takes place in massive stars around 1.5 times bigger than the sun. A proton is added to carbon, which becomes nitrogen, which in turn becomes oxygen when an additional proton is added. Oxygen then radioactively decays and formed helium and carbon, and the process repeats.