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Neutron Star. Gravitational Crush. The balance point to maintain degenerate matter is 1.4 M . When the mass of the core is greater than 1.4 M , electrons cannot support the gravitational force. This is the Chandrasekar limit : beyond that it’s supernova. white dwarf. supernova.
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Gravitational Crush • The balance point to maintain degenerate matter is 1.4 M. • When the mass of the core is greater than 1.4 M, electrons cannot support the gravitational force. • This is the Chandrasekar limit: beyond that it’s supernova. whitedwarf supernova
With the pressure and temperature electrons can fuse with protons into neutrons. Degenerate matter is already compressed, but there are both electrons and nuclei. Neutrons electron proton nucleus neutrons only - fewer particles neutron
Neutron Core • The packed neutrons remain and become a neutron star. • Very hot: 200 billion K • Very small: 10 - 30 km, the size of De Kalb county • Very dense: 100 million tons per cm3
Surface Gravity • Surface gravity is proportional to the mass divided by the radius squared. • Mns = M , about 106 Mearth. • Rns = 0.003 Rearth. • The surface gravity, gns = 1011 gearth.
The surface gravity creates tremendous accelerations. Photons from accelerating electrons X-rays from high energy X-ray telescopes in orbit can spot neutron stars in supernova remnants. X-rays
Pulsars • Neutron stars create very large magnetic fields. • Increased spin from collapse • Spin up to 30 Hz (30 times per second) • These pulsars can be observed as repeating flashes of light as the magnetic poles point towards us.
X-ray Pulsars • Pulsars also emit x-rays. • Appear to blink as pulsar spins • Time between blinks = period of the pulsar crab nebula off crab nebula on