Life Cycle of Stars

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Life Cycle of Stars

• Review

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(No Transcript)
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• A star begins with a nebula a cloud of dust
  and gas.
• A nearby explosion causes the nebula to contract.

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• 3. Gravity increases, and the nebula shrinks and
  becomes a protostar (beginning star).
• 4. Collisions and pressure cause an increase in
  temperature.

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• 5. Nuclear fusion begins (hydrogen to helium).
  A star is born!! These are main sequence stars.
• 6. When helium starts to fuse into carbon, the
  star becomes a red giant or a supergiant.

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• 7. Red giants will become a planetary nebula,
  then a hot, dense core of matter- a white dwarf.
• 8. Supergiants will explode into a supernova.

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• 9. Supernovas will either become a neutron star
  or a black hole.

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White Dwarf

• The end of a low mass star (smaller stars).

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Neutron Star

• Larger mass stars end their lives as a neutron
  star, which is extremely dense matter.

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Black Hole

• Larger mass stars can also end as a black hole,
  which is an entity whose gravity is so great that
  nothing , not even light can escape from it.

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What theory explains the origin of the universe?

• The Big Bang Theory

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The Big Bang Theory

• An explosion that produced all the matter and
  energy in the universe.

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When did the Big Bang take place?

• About 14 billion years ago.

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• Is the universe still expanding?
• Yes
• What is the evidence?
• The Red Shift..

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The Red Shift

• When an object is moving away from an observer,
  the light it reflects has wavelengths that are
  shifted toward the red end of the spectrum.

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How did the solar system form?

• From a haze of particles called a nebular cloud.
• Gravity drew these particles together to form the
  sun, the planets, and moons.

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Some astronomers suggest that the solar system
formed

• When a massive star exploded producing a
  tremendous flash of light.
• This is called a supernova.

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When did the solar system form?

• About 4.6 billion years ago.