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The Structure of White Dwarfs & Neutron Stars

Magnetic Field

Neutron stars can be observed in the cosmos as pulsars. These are rapidly rotating neutron stars that send out beams of powerful electromagnetic energy. This appears as a "pulse" due to their rotation, hence the name.

This energy comes from their magnetic fields. A normal star possesses a strong magnetic field. As it collapses, the magnetic field strength, B, increases inversely proportional to the radius squared. As neutron stars have a tiny radius indeed, B can be phenomenally large, say 108 tesla. The magnetic field can exist, despite the superconducting protons (which are diamagnetic) because there is still a normal (though degenerate) electron gas nearer the surface.

The very rapid rotation of the neutron stars, which can have periods of 1 ms, is due to conservation of angular momentum. As the star rotates, it accelerates charged particle in its vicinity, and these emit radiation. This radiation can range from the visual to the x-ray bands, although usually, radio frequencies are detected. Of course the actual process is much more complicated than this.

 

Links

Introduction

Main Sequence

Degeneracy

Degenerate Electron Matter

Formation of Degenerate Stars

The White Dwarf

The Structure of Neutron Stars

Superfluidity

Quark Matter

Magnetic Field

Conclusions

Bibliography

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