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Rock around the Cosmic Clock

Credit: NASA/JPL

Credit: NASA/JPL

By Paul Brook

Astronomers examine pulsar emissions for signs of gravitational waves, but now they believe that an asteroid may have affected the accuracy of one of these “cosmic clocks”.

The full text of this article can be purchased from Informit.

When a massive star reaches the end of its life, a spectacular supernova explosion occurs and most material from the star is flung off into space at speeds of around 10,000 km/s. Since this material has been thrown far and wide, the core of the star is left exposed. This stellar core will now begin a new life as one of two exotic and fascinating objects: either a black hole or a neutron star.

A neutron star is a tiny (as stars go) yet massive object. The mass of one-and-a-half suns is crammed into an object the size of city. If a grain of sand were as dense as a neutron star, it would weigh the same as the Titanic, and that’s just the tip of the iceberg of fascinating neutron star properties. They have a magnetic field that is typically around a trillion times stronger than the magnetic field on Earth, which takes a day to spin once on its axis. The Sun takes about a month. A typical neutron star takes just a second!

The combination of the rapid rotation and strong magnetic field produces mighty electric fields that rip particles out of the neutron star surface at its north and south magnetic poles, and spit them out into space. This process produces radio emissions, so each magnetic pole becomes a beacon, emanating narrow beams of radio waves outwards.

These north and south radio beams are usually not aligned with the rotational axis of the star....

The full text of this article can be purchased from Informit.