Life Cycle of a Star

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Life Cycle of a Star
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• 1st Stage of Life
• Ball of gas and dust that is pulled together by
  gravity
• Nuclear fusion starts as gas cloud becomes denser
  and hotter
• Nuclear Fusion? hydrogen atoms fuse into helium
• Creates the intense energy found in stars

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• Four types of stars make up the life of a star
• Main Sequence
• Giants
• Super Giants
• White Dwarfs

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• Main Sequence (the Sun)
• 2nd stage
• Longest stage
• Hydrogen changes into helium which creates
  enormous amounts of energy
• The size of the star does not change much

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• Giants and Supergiants
• 3rd stage
• Main Sequence star becomes a red giant
• Red giant? star that expands and cools once is
  loses all its hydrogen
• Center shrinks and atmosphere grows large and
  cools

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• White Dwarf ?small hot star that is the leftover
  center of an older star
• Final stage
• Can shine for billions of years before they
  extinguish
• Observe life of a star (link)

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• Hertzprung-Russell Diagram
• Shows the relationship between a stars surface
  temperature and absolute magnitude
• Used to study the lives of stars
• Most stars lie along the main sequence portion of
  the diagram

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• Age of stars
• Average stars become red giants then white dwarfs
• More massive stars explode into a variety of
  objects

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• Supernova? gigantic explosion in which a massive
  star collapses
• Occurs after a massive star uses up its fuel
  source
• Neutron Star? a star that has collapsed to a
  point at which all particles are neutrons
• A neutron star that spins and sends out beams of
  radiation is called a pulsar

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• Black Hole? an object that is so massive that
  light cannot escape its gravity
• Remnants of a supernova
• Astronomers can detect black holes by using X-ray
  telescopes

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Question 1

• What kind of a star is the sun?

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Answer

• Main Sequence

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Question 2

• What is the H-R diagram?

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Answer

• A graph that shows the relationship between a
  stars temperature and absolute magnitude

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Question 3

• What are the four main types of stars?

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Answer

• Main-Sequence
• Giants and Supergiants
• White Dwarfs