Red+Giant

Red Giant Stars convert hydrogen into helium to produce light, as time goes on the helium sinks deeper into the stars core and the hydrogen lessens so it can not create as much energy to support outer layers or the star, while the star is collapsing the pressure and temperature until the helium fuses into carbon. The helium begins to burn, to radiate energy produced by the helium burning the star expands into a Red Giant. This process happens at the end of a stars life which is after about 5 billion years. By Joel Restuccia