Evolution of Stars

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Evolution of Stars

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Hertzsprung Russell Diagrams(H-R Diagrams)

• A graph that shows the relationship of a stars
  TEMPERATURE to its ABSOLUTE MAGNITUDE ( Its
  Brightness)
• Main Sequence Most stars ( 90 of stars)
• Our Sun is a main sequence star.

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H-R Diagram
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H-R Diagram

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H-R Diagrams

• Bright, Hot , Blue stars are in the upper left.
• Dim, Cool, Red stars are in the lower right.
• Temperature in Kelvins is on the x-axis.
• Brightness is on the y-axis. The sun 1 , for
  brightness.

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Sizes Of Stars

• The SMALLEST are Black Holes
• Neutron Stars ( 20 km, billion tons/cc)
• White Dwarf
• Yellows (mediumthe SUN)
• The LARGEST are the Red Supergiants

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Black Holes

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White Dwarf
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Yellow Orange Stars
1. Alpha Bootes 2. 36 light-yrs away. 3. 25
x sun 4. Third brightest star in the sky.
Arcturaus is an orange giant
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Red Giants

Red Giant
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Red Super Giants

• Red Giants
• It was found that Betelgeuse is one of the
  largest stars, almost the size of our whole solar
  system.

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Betelgeuse A Red Super Giant
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Compare the Sizes of Stars
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The Evolution of Stars
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Evolution of Stars

• Stars are created in nebulae.
• Stars use up their nuclear fuel.
• Stars change over time.
• Stars Age like a living thing does.
• Stars die

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A Nebula
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A Planetary Nebula An Old Star
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Stellar Evolution
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Life of the Sun
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Life of the Sun
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Atoms are made in starsYOU are star-stuff
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Galaxies

• Our galaxy is the Milky Way.
• It is part of a cluster or many galaxies known as
  the Local Group.

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Galaxy Types

• Elliptical Shaped like a football.

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Galaxies

• Spiral Spiral arms wind out from a center.

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Galaxies

• Irregular many unusual shapes

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Doppler Shift

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Doppler Shift

• In 1925, Edwin Hubble found that most galaxies
  are moving away from one another.
• He used Doppler Shift ( p.694)
• Wavelengths of light moving away are stretched
  They shift to Red ( Red Shift).
• Galaxies moving closer to us shift to blue
  wavelengths of light.

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SETI

• SETI is a program in which scientists search for
  extraterrestrial intelligence. WEB