Life cycle of stars

tiaslavin99
Mind Map by tiaslavin99, updated more than 1 year ago
tiaslavin99
Created by tiaslavin99 about 6 years ago
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Life cycle of stars p2

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Life cycle of stars
  1. How is a star formed
    1. 1. Gravity pulls the dust and gas together
      1. 2. As the gas joins together it gets hot. A star forms when it is hot enough for a nuclear reaction to take place. This releases energy and keeps the star hot
        1. 3. During the 'main sequence' period of its life cycle, a star is stable because the forces in it are balanced. The outward pressure from the expanding hot gases is balanced by the force of the star’s gravity. Our Sun is at this stable phase in its life.
          1. 4.Gravity pulls smaller amounts of dust and gas together, which form planets in orbit around the star.
          2. What causes a star to reach a certain size
            1. The star provide an outward pressure to balance gravity by pulling everything inwards. Eventually the hydrogen begins to run out and that causes the star to then swirl.
            2. What does it use for a fuel source?
              1. Stars use hydrogen atoms formed in their core for energy until the hydrogen runs out.
              2. What happens at the end of its life?
                1. What happens at the end of a stars life depends on the size of the star. When a star has used up all the hydrogen 'fuel' in its core, the core contracts and no more energy is produced
                  1. Medium sized stars
                    1. when the core of a medium sized stars such as our sun contract6s the outer part expands. It then cools and changes from yellow to red making the star a red giant. While the sun is in its red giant phases, shells of gas are thrown out. These are called planetary nebulas.
                      1. The core of the original star shrinks until it is about the size of the earth. This is a white dwarf, it is very hot and shines very brightly. It is not making energy so it eventually cools down. This causes it to change from white through yellow and red to black. This becomes a black dwarf
                      2. Massive stars
                        1. A massive star uses up all its hydrogen in a few million years. The core starts to contract and the outer part expands as a supergiant. The core suddenly collapses and the whole star explodes. This explosion is called a supernova and the small remaining core is called a neutron star or a black hole if it is really massive. The material thrown out as the core explodes, collide with gas and dust in space and forms a glowing cloud of gas called a supernova remnant. Over a period of time the supernova remnant joins with other dust and gas in space. As gravitational forces act a new star is formed.
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