the formation of a pulsar</p><p>A star in a
Pulsars are highly magnetized, rotating neutron stars
that emit a beam of electromagnetic radiation
. The radiation can only be observed when the beam of emission is pointing towards the Earth. This is called the lighthouse effect and gives rise to the pulsed nature that gives pulsars their name. Because neutron stars are very dense objects, the rotation period and thus the interval between observed pulses is very regular. For some pulsars, the regularity of pulsation is as precise as an atomic clock
. The observed periods of their pulses range from 1.4 milliseconds
to 8.5 seconds. A few pulsars are known to have planets orbiting them, such as PSR B1257+12
. Werner Becker of the Max Planck Institute for Extraterrestrial Physics
said in 2006, "The theory of how pulsars emit their radiation is still in its infancy, even after nearly forty years of work."Press Release
: . European Space Agency, 26 July 2006.
The events leading to the formation of a pulsar begin when the core of a massive star is compressed during a supernova
, which collapses into a neutron star. The neutron star retains most of its angular momentum
, and since it has only a tiny fraction of its progenitor's radius (and therefore its moment of inertia
is sharply reduced), it is formed with very high rotation speed. A beam of radiation
is emitted along the magnetic axis of......