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Neutron Starquakes and Neutron Star structure. Like the Earth, except with neutron stars. Really. What exactly is a neutron star?. A normal star’s equilibrium is maintained by the heat from the fusion in the core.
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Neutron Starquakes and Neutron Star structure Like the Earth, except with neutron stars. Really.
What exactly is a neutron star? • A normal star’s equilibrium is maintained by the heat from the fusion in the core. • Neutron stars collapsed in on themselves until they became very big atoms and then collapsed some more. • Classical forces cannot support this mass against gravity • Pauli pressure – dominant equilibrium P = A xdensity(5/3) or Bxdensity(4/3)
What is nice • They differ only in mass, spin, angle between axes, and magnetic fields. • These are all visible • No chemistry • Small ranges of variation • Magnetic force (visible field controlling motion) This is about how different they get
What is less nice • Non-classical physics • Counterintuitive quantum effects for pressure • Relativistic effects for spin • Interference in observation (spin, magnetic, atmosphere)
Neutron star structure • Rigid crust over superfluid (true zero viscosity) core • Fast spin • Charged interior, conductive exterior with force from magnetic field
Neutron starquakes • Decaying magnetic field • Change of equilibrium-shape with spin-down • Sudden change in angular velocity • What is wrong with this model?
Cases • 2004, SGR 1806-20Gamma-ray flare • Quasi-Periodic Oscillations (QPOs) detected (free oscillations)
There is a problem in this model • Predicted:Angle increases with time • Observed:Angle increases in young neutron stars, but then changes randomly
References: • Franco, Link, Epstein, Nov. 1999 • Watts, Strohmayer; Jan 2007 • NASA (images)