What is the triple-alpha process or helium burning?
• Nuclear Energy in Stars • We showed in previous lectures that chemical energy was insufficient to power the Sun. Even gravitational energy, which could provide the Sun’s luminosity by shrinking by 40 meters every year, could only do so for millions of years, not the billions that the Sun has lasted. • Since the gravitational and the electromagnetic forces are insufficient to provide the energy of the Sun, we turn to the remaining forces: the strong and weak nuclear forces. In particular, it is the strong nuclear force that can provide us this energy. • The strong nuclear force is the force that holds protons and neutrons together in the nucleus of the atom, overcoming the mutual electrical repulsion of the protons. The strong force is carried by particles called gluons, which hold together the quarks that make up protons and neutrons. (Electrons are not made up of quarks – they are a different sort of particle called a lepton.) • The weak nuclear force is a force that changes the kin
