Describe in detail the life story of a star.

In space, there exists huge clouds of gas and dust. These, clouds consist of hydrogen and helium, and are the birthplaces of new stars. Gravity causes these clouds to shrink and become warmer. The body starts to collapse under its own gravity, and the temperature inside rises. After the temperature reaches several thousand degrees, the hydrogen molecules are ionized (electrons are stripped from them), and they become single protons.

The contraction of the gas and the rise in temperature continue until the temperature of the star reaches about 10,000,000 degrees Celsius (18,000,000 degrees Fahrenheit). At this point, nuclear fusion occurs in a process called proton-proton reaction.

Briefly, proton-proton reaction is when four, protons join together and two are converted into neutrons an 4He nucleus is formed. During this process, some matter is lost and converted to energy as dictated by Einstein’s equation. At this point, the star stops collapsing because the outward force of heat balances the gravity.

The proton-proton reaction occurs during a period called the hydrogen-burning state, and its length depends on the star’s weight. In heavy stars, the great amount of weight puts a large amount of pressure on the core, raising the temperature and speeding up the fusion process. These heavy stars are very bright, but only live for a short amount of time.

After the energy from this deuteron-hydrogen fusion process ends, the star begins to contract again, and the temperature and pressure subsequently increase. Nuclear fusion occurs between the hydrogen and lithium and other light metals in the star, but this process soon ends.

Contraction starts, again, and the extreme high temperature and pressure cause the hydrogen to transform into helium through the carbon-nitrogen-oxygen cycle. When all the hydrogen has been used up, the star is at its largest size, and it is called a red giant.