Astronomy

The Facts about Pulsars



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Pulsars are amazing astronomical objects. The most accurate definition of a pulsar is that they are fast rotating neutron stars. Pulsars begin with a supernova explosion. A supernova occurs when a very massive star collapses and then explodes. This occurs when a star's core runs out of fuel. The outer part of the star begins to fall into the core, causing massive amounts of energy to be generated.

If these stars have four to eight times the mass of our sun, a neutron star will form. In other words all of the gas and matter will fall in on itself. When this occurs the speed and gravity involved is so strong it fuses everything together. This occurs in a matter of seconds. A star that was once much larger than our sun has now become only about ten to twelve miles in diameter.

The energy involved in this process is so great that it forces electrons and protons together to form neutrons. This is why it is called a neutron star.

The neutron star is so dense that a handful of it would weight about 100 billion tons. A neutron star is also spinning very rapidly. There is one located in the crab nebula that is spinning at an astonishing 33 times per second.

Neutron stars possess a strong gravitational pull. It is so strong that it can bend light. Neutron stars also possess a powerful magnetic field, perhaps a trillion times stronger than earth's magnetic field. It is the combination of the magnetic field and high speed rotation that is responsible for pulsars.

Pulsars were first discovered by graduate student Jocelyn Bell in 1967. She was able to isolate and identify radio sources that appeared to blink on and off.

What has since been discovered, is that the magnetic field of neutron stars is so strong and the spin of the star so rapid, that it causes the light and radiation emitted by the star to form cones of emission, streams of light and radiation, much like you would see at a lighthouse.

These streams of light and radiation can be seen from earth; when they cross earth's line of sight. Also the magnetic and rotational axis of a neutron star is not aligned and this produces the blinking, or on and off affect that we detect.

There is also another kind of pulsar known as "accretion powered pulsars." This occurs when a neutron star is orbited by a normal star to form a binary system. The gravitational pull of the neutron star actually pulls material from the normal star. This material, in the form of gases and electrons becomes so heated that x-rays are generated. These hot-spots produce x-ray pulses;which can also be detected.

Thus, pulsars are rapidly spinning neutron stars, that produce streams (or cones)of light; including radio waves, that can be detected from earth.

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