Life Cycle of a Star

• Nebula


  Stars form from a giant cloud of hydrogen gas and dust, called a nebula. These particles are drawn together by gravity
• Compression 


  Force of gravity within the nebula pulls the particles closer together, and there is very high temperatures. Nuclear reactions begin and hydrogen fusion reactions increase
• Beginning sequence/protostar 


  Once hot enough, nuclear fusion reactions occur from its core. Hydrogen nuclei will fuse to form helium nuclei. Every fusion reaction releases heat, light and energy, which keeps the core hot. Fusion reactions occur and the star is in equilibrium
• Main Sequence 


  Star is born and is in equilibrium and stable. The inward force is equal to the outward pressure force
• Red Giant


  After billions of years, the star will begin to run out of hydrogen. Fusion reactions in the core will die down, causing the core to shrink because the inward force (gravity) will become greater than the outward force as the pressure dies down. As the core shrinks more reactions cause the outer part to expand
• Supernova 


  A star much bigger will contract and become unstable. It explodes, throwing gas and dust into space.
• White dwarf


  A star will eventually become unstable and eject the outer layer of dust and gas. the core will collapse completely and become a white dwarf
• Neutron star


  Any matter remaining will form a very dense neutron star
• Black hole 


  If the neutron star has a mass of 5x the Sun, it will collapse into a black hole