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After the Supernova: Pulsars

After the Supernova: Pulsars. Melissa Anholm University of Wisconsin-Milwaukee 29 September, 2008. Outline. Properties of Neutron Stars Large Magnetic Field Rapid Rotation Origin of the Pulsing Effect Motion in a Magnetic Field Light Emission The Lighthouse Effect.

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After the Supernova: Pulsars

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  1. After the Supernova:Pulsars Melissa Anholm University of Wisconsin-Milwaukee 29 September, 2008

  2. Outline • Properties of Neutron Stars • Large Magnetic Field • Rapid Rotation • Origin of the Pulsing Effect • Motion in a Magnetic Field • Light Emission • The Lighthouse Effect

  3. Properties of Neutron Stars A Typical Neutron Star • Strong Magnetic Field • Fast Rotation

  4. Properties of Neutron Stars Why does it spin so fast? A typical star completes about one rotation every week - month. A typical young pulsar completes about one rotation per second.

  5. Properties of Neutron Stars Magnetic Fields - Now with Lines! http://www.freewebs.com/ayxl/magnet.jpeg http://www.utm.edu/staff/cerkal/magnetic_files/image004.jpg

  6. Properties of Neutron Stars After the Collapse: Rotation and the Magnetic Field • Dense magnetic field lines • Strong magnetic field • Angular momentum conserved • Fast rotation • Magnetic and rotational • axes may not be aligned.

  7. Origin of the Pulsing Effect Misalignment of Magnetic and Rotational Axes - Why We Care All newly formed neutron stars (and some older ones, too!) produce beams of light along their magnetic poles if the axes aren’t aligned. http://www.atnf.csiro.au/news/press/images/binary_pulsar/

  8. Origin of the Pulsing Effect Properties of Light • “photon” = a particle of light • accelerating charged particles produce photons (!)

  9. Origin of the Pulsing Effect A Strange Connection between Electricity and Magnetism • Moving magnets produce an • electric force. • Electric currents and moving • charged particles produce a • magnetic force. • Result: a moving charged • particle in a magnetic field • will accelerate. http://img105.imageshack.us/img105/5114/magfield0ct.jpg

  10. Origin of the Pulsing Effect Motion on a Large Scale Near a Rotating Magnet Charged particles move upward or downward (depending on the charge) at the pulsar’s rotational poles. http://www.atnf.csiro.au/news/press/images/binary_pulsar/

  11. Origin of the Pulsing Effect Motion in a Magnetic Field • A charged particle placed in a • magnetic field will spiral around • the magnetic field lines.

  12. Origin of the Pulsing Effect Accelerating A Charged Particle • Light is emitted in a • direction perpendicular • to the magnetic field. Synchrotron Radiation = Light

  13. Origin of the Pulsing Effect The Lighthouse Effect

  14. http://www.shatters.net/forum/viewtopic.php?t=11372 Conclusions • Pulsars are rapidly rotating neutron • stars with powerful magnetic fields. • A misalignment in the rotational • and magnetic axes leads to the • emission of beams of light from • a pulsar’s magnetic poles.

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