Life Cycle of Stars

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Life Cycle of Stars
Our Sun, 5 By (Ga) and counting (each step 150
My) Martin Rees - Our Cosmic Habitat
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Life Cycle of Stars
Low Mass 1 trillion yr (67 x age of universe -
Tu) Solar Mass 10 By (1.5 x Tu) High Mass
-100 My (150 cycles in Tu) Very High Mass -1 My
(15 000 cycles) Martin Rees - Our Cosmic Habitat
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Life Cycle of Stars

• Recycling
• Supernovae produce
• - heavy elements
• neutron stars
• black holes
• Martin Rees - Our Cosmic Habitat

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4 Main star types
vertical scale L Brightness
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Stars close to our own
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How did the Sun get on the Main Sequence?
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How will the Sun leave the Main Sequence?
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The Sun becomes a Red Giant
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The Sun Engulfs the Inner Planets
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The Sun becomes a White Dwarf
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Brightest Star Sirius A (Sirius B is a white
dwarf)
Orion Constellation ( Nebula)
Sirius
Comet Hale-Bop
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• This is a Hubble Space Telescope image - the
  first direct picture of the surface of a star
  other than the Sun.
• While Betelgeuse is cooler than the Sun, it is
  more massive and over 1000 times larger. If
  placed at the center of our Solar System, it
  would extend past the orbit of Jupiter.
• Betelgeuse is also known as Alpha Orionis, one of
  the brightest stars in the familiar constellation
  of Orion, the Hunter.
• The name Betelgeuse is Arabic in origin. As a
  massive red supergiant, it is nearing the end of
  its life and will soon become a supernova. In
  this historic image, a bright hotspot is revealed
  on the star's surface.

Betelgeuse is a red supergiant star about 600
light years distant
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The Crab Nebula (AD 1054) 6300 Ly
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• The Crab Nebula
• The result of a star that was seen to explode in
  1054 AD.
• This spectacular supernova explosion was recorded
  by Chinese and (quite probably) Anasazi Indian
  astronomers.
• The filaments are mysterious because they appear
  to have less mass than expelled in the original
  supernova and higher speed than expected from a
  free explosion.
• In the above picture taken recently from a Very
  Large Telescope, the color indicates what is
  happening to the electrons in different parts of
  the Crab Nebula.
• Red indicates the electrons are recombining with
  protons to form neutral hydrogen, while blue
  indicates the electrons are whirling around the
  magnetic field of the inner nebula.
• In the nebula's very center lies a pulsar a
  neutron star rotating, in this case, 30 times a
  second.

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Crab Nebular Pulsar
The images were obtained with the Hubble Space
Telesope by Jeff Hester and Paul Scowen of the
Arizona State University
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Supernova 1987a
Supernova 1987A is located 167,000 light-years
away from Earth in the Large Magellanic Cloud.
Hubble Space Telescope
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• Supernova 1987a
• In 1987, the brightest supernova in recent
  history occurred in the Large Magellanic Clouds.
• At the center of the picture is an object central
  to the remains of the violent stellar explosion.
• When the Hubble Space Telescope was pointed at
  the supernova remnant in 1994, however, curious
  rings were discovered.
• The origins of these rings still remains a
  mystery.
• Speculation into the cause of the rings includes
  beamed jets emanating from a dense star left over
  from the supernova, and a superposition of two
  stellar winds ionized by the supernova explosion.
  

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Expansion of 1987a
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