This is the process and the evolution of a Solar Mass Star:
- The star’s core is made up of helium and surrounded by a hydrogen shell.
- As hydrogen burns faster, it comes to an end and is not sufficient for helium to start burning.
- The radiactive pressure goes outwards to resist gravitational collapse. In the outer regions temperature increases and hydrogen fusion can occur.
- The core continues to collapse and the outer regions keep increasing their temperature and luminosity. Now everything exerts a pressure.
- Pressure makes the outer layers to expand, they cool down and the star becomes redder. After millios of years the hydrogen shell runs out of fuel.
- The star turns into a red giant and is seen as a nebula leaving a core behind.
- The core has half of the mass of a star and will eventually cool down.
- The atoms are packed and the star turns into a white dwarf.