Supernovae and Neutron Stars
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Transcript of 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 e+p > 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 Nebula…the 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/sounds.html
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Pulsar properties
• Highly regular pulse properties
• PSR0329+54, P=0.714519699726 sec
• PSR1633+24, P=0.4905065128003 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 mystery…
pulsar masses are nearly all AT
the Chandrasekh
ar Limit
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Periods and Period Derivatives for Pulsars