The Neutron Predicted by Ernest Rutherford in 1920
Experimentally discovered by James Chadwick in 1932
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The Neutron Star Fritz Zwicky and Walter Baade mathematically
predicted the existence of a neutron star in 1934.
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Massive Star Life Cycle
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The Discovery of the Pulsar Jocelyn Bell discovers the first
pulsating star (pulsar for short) using a radio telescope in 1967.
The star pulsed once every 1.3 seconds.
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Pulsars and Their Relation to Neutron Stars By 1968, with the
discovery of the Crab and Vela pulsars in Supernova Remnants, MOST
scientists believed that pulsars were in fact neutron stars. Crab
Pulsar in the Crab nebula
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How do Neutron Stars Form
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What is a pulsar? A pulsar is a rapidly rotating neutron star
that beam radio waves towards Earth. This brings up some new
questions... What is a neutron star? Why is it rotating? Why is it
beaming radio waves?
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Life of a Massive Star Stars spend most of their lives fusing
hydrogen into helium The star is literally blowing itself apart
while gravity tries to crush it When a star runs out of hydrogen it
tries to fuse heavier elements
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Death of a Massive Star No energy can be extracted by fusing
iron Without a source of energy, what do you think will happen to
the star? Watch and see: http://www.youtube.com/watch?v=p8Hc
DnhkM3I
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Supernovae 1. Gravity causes the outer layers to collapse at
super-sonic speeds 2. When outer layers hit the Iron core, they
pile up and bounce back 3. Most of the star explodes
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A Neutron Star is Born The star's core is left behind and goes
through a wild transformation What was once a core of Iron is now a
super- dense neutron star Write and equation to represent what is
happening here.
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Electron Capture (inverse Beta decay) Beta Decay Process
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Neutron Star Facts Diameter, Mass, Temperature and Rotation 1.4
times as massive as our Sun (500,000 Earth masses 40% more massive
than our Sun) About 12 miles across 1 teaspoon would weigh 5.5
billion tons 10 million F at birth Some spin several times a second
or faster Why do neutron stars spin?
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The more massive the Progenitor Star the smaller the Remnant
Stellar Remnant Size Comparisons
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Neutron Star: Mass and Diameter 1.4 times as massive as our Sun
(500,000 Earth masses 40% more massive than our Sun) About 12 miles
across Calculate the density of a neutron star Density =
Mass/Volume
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Density Extremely dense objects 100,000,000,000,000,000 kg m -3
Next thing down from a black hole
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Your weight
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Calculate your weight on a neutron star applet
http://www.exploratorium.edu/ronh/weight/
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Neutron star properties Extremely rapid spin Rotation rates in
excess of 700 Hz Speed at surface ~ significant fraction of c
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Neutron Star Facts Neutron stars can also highly magnetized
Fields thousands billions times stronger than the strongest man
made magnets This has an amazing effect Neutron stars can emit
beams of radio waves
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Do You See a Pulsar? Pulsars are like interstellar lighthouses
If the beam points towards Earth, we see a pulse of radio
waves
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Sounds of Pulsars
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What did you notice?
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Pulsar Recycling Some pulsars spin faster than others When the
pulsar period is a few milliseconds, we call it a millisecond
pulsar MSPs are actually recycled pulsars and are the most exciting
kinds
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Pulsar Recycling Some pulsars spin faster than others When the
pulsar period is a few milliseconds, we call it a millisecond
pulsar MSPs are actually recycled pulsars and are the most exciting
kinds