Neutron Stars

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Neutron Stars
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White dwarf
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Mass limit for White Dwarf

• MCh 1.46 Msun

S. Chandrasekhar
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Inverse ßdecay
neutron
proton
electron
neutrino
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Degeneracy Pressure

• Pauli exclusion principle
• Heisenberg uncertainty priniple
• P nvp
• Distribution function for fermions
• Pressure

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Simple Calculation!

• If M 2 Msun then R 15 Km

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H-R Position
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Features
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Features

• Radius 10 km

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Features

• Radius 10 km
• Period 0.001s 6.0 s
• The Sun at 15 km would rotate 700 times per
  second

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Features

• Radius 10 km
• Period 0.001s 6.0 s
• Density 1014g/cc
• 1012 times higher than the density
• in the Sun

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Features

• Radius 10 km
• Period 0.001s 6.0 s
• Density 1014g/cc
• Gravity 21012 m/s2
• 21011 times that of Earth

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Features

• Radius 10 km
• Period 0.001s 6.0 s
• Density 1014g/cc
• Gravity 21012 m/s2
• gravitational redshift

600 nm gt 720 nm
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Features

• Radius 10 km
• Period 0.001s 6.0 s
• Density 1014g/cc
• Gravity 21012 m/s2
• gravitational redshift

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Features

• Radius 10 km
• Period 0.001s 6.0 s
• Density 1014g/cc
• Gravity 21012 m/s2
• gravitational redshift
• escape velocity 0.4c 0.8c
• if an average human were to encounter a
  neutron star, they would impact with roughly the
  energy yield of a 100 megaton nuclear explosion

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Features

• Radius 10 km
• Period 0.001s 6.0 s
• Density 1014g/cc
• Gravity 21012 m/s2
• Magnetic field 1012 Gauss
• Magnetic field of Earth at poles 0.6 Gauss

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Features

• Radius 10 km
• Period 0.001s 6.0 s
• Density 1014g/cc
• Gravity 21012 m/s2
• Magnetic field 1012 Gauss
• Earth with R 5m could produce such magnetic
  field.

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Mass Limit

• By Oppenheimer Volkoff
• MOV 3.2 Msun

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Mass Limit

• Tolman-Oppenheimer-Volkoff (TOV) equation

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More Mass!
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Neutron Star Pizza
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Core

• Superfluidity degenerate neutrons can flow
  without any friction.
• Superconductivity electrical currents inside the
  neutron star can travel around without
  experiencing any electrical resistance.
  Therefore, once you start an electrical current
  it keeps going forever.
• Neutronium
• Strange matter

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Physics in Core

• We need three physical theories to understand
  their dense interiors
• Relativity theory is needed because so much mass
  occupies such a small space that space-time is
  warped.
• Nuclear theory is needed both because the crust
  on neutron stars is made of iron and nickel
  nuclei, and the pressure in the interior is so
  great that nuclei are torn apart into their
  individual nucleons.
• Quantum mechanics is needed to properly
  understand this microworld.

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History

• 1930 Lev Davidovic Landau
• 1931 S. Chandrasekhar
• 1932 Sir James Chadwick
• 1933 Walter Baade Fritz Zwicky
• 1939 J. R. Oppenheimer G. M. Volkoff
• 1967 Jocelyn Bell Anthony Hewish
• 1971 Riccardo Giacconi

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Supernova 1987a
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Crab Nebula
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Neutron Stars

• Pulsars
• X-ray Brusters
• Magnetars

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Pulsars

• In 1967 at Cambridge University, Jocelyn Bell
  observed a strange radio pulse that had a regular
  period of 1.3373011 seconds

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Pulsars
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Pulsar or Neutron Star
Pulsar Neutron Star
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Pulsars

• Lighthouse

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Sound of Pulsars!
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PSR B032954

• This pulsar is a typical, normal pulsar, rotating
  with a period of 0.714519 seconds, i.e. close to
  1.40 rotations/sec

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PSR B0833-45, The Vela Pulsar

• This pulsar lies near the centre of the Vela
  supernova remnant, which is the debris of the
  explosion of a massive star about 10,000 years
  ago. The pulsar is the collapsed core of this
  star, rotating with a period of 89 milliseconds
  or about 11 times a second.

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PSR B053121, The Crab Pulsar

• This is the youngest known pulsar and lies at the
  centre of the Crab Nebula, the supernova remnant
  of its birth explosion, which was witnessed by
  Europeans and Chinese in the year 1054 A.D. as a
  day-time light in the sky. The pulsar rotates
  about 30 times a second.

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PSR J0437-4715

• This is a recently discovered millisecond
  pulsar, an old pulsar which has been spun up by
  the accretion of material from a binary companion
  star as it expands in its red giant phase. The
  accretion process results in orbital angular
  momentum of the companion star being converted to
  rotational angular momentum of the neutron star,
  which is now rotating about 174 times a second

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PSR B193721

• This is the fastest known pulsar, rotating with
  a period of 0.00155780644887275 seconds, or about
  642 times a second. The surface of this star is
  moving at about 1/7 of the velocity of light

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Binary Pulsars
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X-Ray Blusters
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Magnetar

• Soft Gamma Repeater (1979)
• (SGRs)

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Magnetar

• Theory by Dr.Robert Duncan (1992)
• A nuetron star with a super-strong magnetic field
• SGR 1806-20 T7.5 s
• magnetic field strength of about 800 trillion
  Gauss
• Normal radio pulsars reach about 1 trillion to 5
  trillion Gauss

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Schrödinger

• Schrödingers equation for electron in
  electromagnetic field

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Magnetar

• At the surface of the star a chunk of
  magnetizable metal like iron would feel a force
  equal to 150 million times the Earth's
  gravitational pull on it
• magnetism itself can keep the star hot - about 10
  million degrees C

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Recent Expriment

• The RHIC relativistic nuclear collider at
  Brookhaven and the LHC hadron collider at CERN
  Geneva were built precisely to investigate the
  micro-world which inhabits neutron star
  interiors.

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Neutron Star in IRAN
Its ME!!
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Summary

• Neutron stars are the most interesting objects
  that observed

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References

• BOOKS
• Astrophysics of Neutron Stars, V.M. Lipunov
• WEB
• http//science.nasa.gov
• http//en.wikipedia.org
• http//rainman.astro.uiuc.edu
• http//atropos.as.arizona.edu
• http//antwrp.gsfc.nasa.gov
• http//woodall.ncsa.uiuc.edu
• http//chandra.harvard.edu

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By

• Hossein Alisafaee
• 8111017
• Automn 1383
• THANKS ALL