What does nuclear fusion have to do the death and birth of stars?
stars keep their energy output through process known as fusion.
Stars are formed when a huge cloud of gas and dust collapse due to gravity,.AS the mass increases it attracts more gas and dust,. Due to very high pressure at center temperature increases and when it reaches about 15 million degree K hydrogen fusion starts and a star is born. It remains in main sequence and fusion continues till all the hydrogen is exhausted. picture crdit enchanted learning.com.