Why does a pulsar rotate

One such object is neutron stars. These stars are formed from the gravitational collapse following the death of a massive star. Neutron stars are the tiny — but incredibly dense — remnants that are left behind after such a collapse.

Immediately after a star goes supernova, gravity begins to take individual atoms of matter together and compress them. This ignites a chain reaction, where individual electrons are effectively pushed into the protons, converting them into uncharged neutrons. The gravity is so strong during the collapse that the electrons are converted into something else — neutrons — to fulfill the exclusion principle.

This is what prevents the star from becoming a singularity or a black hole. As an aside, the key difference between the formation of a white dwarf also a very dense remnant that is formed from the death of a sunlike star and neutron stars is that the atoms do remain intact, but have been pulled incredibly close together.

This, in essence, is the result of millions of years worth of fusion that happens in only a split second! The final product has a density equal to trillion times that of water — yes you heard right: One hundred trillion.

A spinning magnetic field generates an electric field , which, in turn, can cause charged particles to move creating an electric current. The region above the surface of the pulsar that is dominated by the magnetic field is called the magnetosphere. In this region, charged particles like electrons and protons, or charged atoms, are accelerated to extremely high speeds by the very strong electric field.

Any time charged particles are accelerated meaning they either increase their speed, or change direction , they radiate light. On Earth, instruments called synchrotrons accelerate particles to very high speeds and use the light they radiate for scientific studies. In the pulsar's magnetosphere, this basic process may generate light in the optical and X-ray range. But what about the gamma-rays emitted by a pulsar?

Observations show that gamma-rays are emitted from a different location in the space surrounding the pulsar than the beams of radio waves, and at a different altitude above the surface, Harding said. And, rather than in a narrow, pencil-like beam, gamma-rays are emitted in a fan shape. But just as with radio wave emissions, scientists are still debating the exact mechanism responsible for generating gamma-rays from a pulsar. Scientists discovered pulsars by using radio telescopes, and radio continues to be the primary means of hunting these objects.

Because pulsars are small and faint compared to many other celestial objects, scientists find them using all-sky surveys: A telescope scans the entire sky, and over time, scientists can look for objects that flicker in and out of view. The Parkes radio telescope in Australia has found the majority of known pulsars.

Other telescopes that have made major contributions to pulsar searches are the Arecibo radio telescope in Puerto Rico, the Green Bank Telescope in West Virginia, the Molonglo telescope in Australia, and the Jodrell Bank telescope in England. Thousands of new pulsars may be detected by two radio survey telescopes that are scheduled to start taking data in the next five years, according to Scott Ransom, a staff astronomer at the National radio Astronomy Observatory NRAO in Charlottesville, Virginia.

The organization's website says early science observations could begin in , but the array would not reach full science operations both facilities until The Fermi Gamma-ray Space Telescope, launched in June , has detected 2, gamma-ray-emitting pulsars , including 93 gamma-ray millisecond pulsars.

Fermi has been particularly helpful because it scans the entire sky, whereas most radio surveys typically scan only sections of the sky along the plane of the Milky Way galaxy. Detecting different wavelengths of light from a pulsar can be difficult.

A pulsar's beam of radio waves might be very powerful, but if it doesn't sweep across the Earth and enter a telescope's field of view , astronomers may not see it. The gamma-ray emission from a pulsar may fan across a larger area of the sky, but it also can be dimmer and more difficult to detect. As of March 22, , scientists know about 2, pulsars for which only radio waves have been detected, and about pulsars that radiate gamma rays.

Scientists now know of millisecond pulsars, 60 of which radiate gamma rays, Ransom said. These numbers change frequently as new pulsars are discovered. The light emitted by a pulsar carries information about these objects and what is happening inside them. That means pulsars give scientists information about the physics of neutron stars, which are the densest material in the universe with the exception of whatever happens to matter inside a black hole.

Under such incredible pressure, matter behaves in ways not seen before in any other environment in the universe. The strange state of matter inside neutron stars is what scientists call " nuclear pasta ": Sometimes, the atoms arrange themselves in flat sheets, like lasagna, or spirals like fusilli, or small nuggets like gnocchi.

Pulsars are rotating neutron stars observed to have pulses of radiation at very regular intervals that typically range from milliseconds to seconds. Pulsars have very strong magnetic fields which funnel jets of particles out along the two magnetic poles. These accelerated particles produce very powerful beams of light.

Often, the magnetic field is not aligned with the spin axis, so those beams of particles and light are swept around as the star rotates. When the beam crosses our line-of-sight, we see a pulse — in other words, we see pulsars turn on and off as the beam sweeps over Earth.

One way to think of a pulsar is like a lighthouse. At night, a lighthouse emits a beam of light that sweeps across the sky. Even though the light is constantly shining, you only see the beam when it is pointing directly in your direction. The video below is an animation of a neutron star showing the magnetic field rotating with the star. Massive, fast-spinning objects that are not perfectly symmetrical are predicted to radiate away energy in these waves, with faster objects unleashing much more energy than slower ones.

The authors agree, saying that slowing from gravitational wave emission must become significant at spin rates higher than Hz or that theorists should revise their models of neutron star crusts, which were used to arrive at the Hz limit. They estimate its mass at about twice that of the Sun — in line with previous pulsar observations.

The pulsar was found in a cluster of billion-year-old stars called Terzan 5, which lies 28, light years away near the centre of the galaxy.