Chapters 14 and 15 Stellar Evolution and Stellar Remnants

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Chapters 14 and 15 Stellar Evolution and
Stellar Remnants
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Star Birth Nebula

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Young star Protostar
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Adult Main Sequence

• As the temperature in the interior rises,
  nuclear reactions produce outward force and
  balances the inward force of gravity ?
  hydrostatic equilibrium star becomes stable and
  contraction stops?main-sequence star

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Energy Sources in Stars

• 4 hydrogen nuclei fuse to become 1 helium nucleus
• Since the mass of 4 hydrogen nuclei is greater
  than the mass of 1 helium nucleus, the leftover
  mass (0.7) is converted to energy by Einsteins
  equation Emc2

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The end states of stars depends upon its mass!
The more massive a star, the faster it consumes
its fuel, the shorter its lifetime
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A B C
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Evolution of Low Mass Stars including our Sun M
lt 10 Solar Masses
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Old Age Red Giant
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Elderly, core White Dwarf
The core of the white dwarf star is now all
carbon and oxygen
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Elderly, envelope Planetary nebula
Ring Nebula
Eskimo Nebula
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Yeah, but what about the really Massive stars?
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Old Age Red Supergiant
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Figure 13.19
Elderly, dying starSupernova
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Super Nova Remnants
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Our Sun will never explode. Only massive stars
explode as supernova!
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Elderly, core Neutron Star
Core
High mass stars becomes so dense that
protons and electrons combine to become neutrons
and star becomes neutron star
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Life Cycle of a Low Mass Star
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Life Cycle of a High Mass Star