Supernovae and Neutron Stars

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Supernovae and Neutron Stars
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Specific textbook sections

• Evolution after the main sequence Section 19.4
• White dwarf stars Section 20.1
• Supernovae and neutron stars Section 20.2

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Core collapse of a massive star has two
consequences

• Massive explosion (1044 Joules)
• Production of a neutron star

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Formation of a neutron star from stellar core

• As core collapses, matter becomes compressed
• Electrons and protons forced together ep gt n
  nu (neutronization)
• Core of the becomes a neutron fluid
• Neutronization produces a burst of neutrinos
• Neutron fluid in core becomes degenerate and
  rigid

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The physics of a self-gravitating neutron blob
(neutron star)

• Radius versus mass relation for neutron star
• Notice size of neutron star
• Masses extend above Chandrasekhar limit

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Theoretical prediction of the existence of a
neutron star

• The remnant after the explosion of a massive star
• An object having the mass of the Sun (or more)
  but in an object with the diameter of Iowa City!
• An equivalent to the Chandrasekhar mass (largest
  possible mass of a neutron star)
• Do they exist?

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The problem of the Crab Nebulathe remnant of the
supernova of 1054 AD

• Even today,something is powering the Crab Nebula,
  causing it to shine at x-rays

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1968 The Discovery of Pulsars Rotating Neutron
Stars
http//www.jb.man.ac.uk/pulsar/Education/Sounds/s
ounds.html
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Pulsar properties

• Highly regular pulse properties
• PSR032954, P0.714519699726 sec
• PSR163324, P0.4905065128003 sec
• What in nature could provide such a perfect
  clock?
• Demo

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Pulsars as rotating neutron stars
demo
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The Crab Nebula Pulsar
http//chandra.harvard.edu/photo/2002/0052/movies.
html
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How many pulsars (neutron stars) are there in the
sky?
http//www.atnf.csiro.au/research/pulsar/psrcat
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Neutron stars from exotica to numerous
astronomical objects
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A final mysterypulsar masses are nearly all AT
the Chandrasekhar Limit
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Periods and Period Derivatives for Pulsars