Why do pulsars spin

Materials provided by North Carolina State University. Note: Content may be edited for style and length. Science News. Their findings are published in the Jan. ScienceDaily, 26 February North Carolina State University. As a result, scientists can watch for changes in a pulsar's blinking that could indicate something happening in the space nearby. It was with this method that scientists began to identify the presence of alien planets orbiting these dense objects.

In fact, the first planet outside Earth's solar system ever found was orbiting a pulsar. Because pulsars are moving through space while also blinking a regular number of times per second, scientists can use many pulsars to calculate cosmic distances.

The changing position of the pulsar means the light it emits takes more or less time to reach Earth. Thanks to the exquisite timing of the pulses, scientists have made some of the most accurate distance measurements of cosmic objects. Pulsars have been used to test aspects of Albert Einstein's theory of general relativity, such as the universal force of gravity. The regular timing of pulsars also may be disrupted by gravitational waves — the ripples in space-time predicted by Einstein and directly detected for the first time in February There are multiple experiments currently searching for gravitational waves via this pulsar method.

Using pulsars for these types of applications depends on how settled they are in their rotation thus providing very regular blinks , Ransom said. All pulsars are slowing down gradually as they spin; but those used for precision measurements are slowing down at an incredibly slow rate, so scientists can still use them as stable time-keeping devices.

All pulsars slow down gradually as they age. The radiation emitted by a pulsar is jointly powered by its magnetic field and its spin. As a result, a pulsar that slows down also loses power, and gradually stops emitting radiation or at least, it stops emitting enough radiation for telescopes to detect , Harding said. Observations thus far suggest that pulsars drop below the detection threshold with gamma-rays before radio waves. When pulsars reach this stage of life, they enter what's known as the pulsar graveyard.

Pulsars that have stopped emitting may be considered ordinary neutron stars by astronomers. When a pulsar forms from the wreckage of a supernova, it spins fast and radiates a lot of energy, Ransom said.

The well-studied Crab Pulsar is an example of such a young pulsar. This phase may last for a few hundred thousand years, after which the pulsar begins to slow down and only emit radio waves. These "middle-age" pulsars likely make up most of the population of pulsars identified as emitting only radio waves, he added.

These pulsars live for tens of millions of years before eventually slowing down so much that they "die" and enter the pulsar graveyard. But if the pulsar sits near a stellar companion, it may be "recycled," meaning it siphons material and energy from its neighbor, increasing its spin to hundreds of times per second — thus creating a millisecond pulsar, and giving the once-dead pulsar new life.

This change can occur anytime in a pulsar's life, meaning a "dying" pulsar's rotation rate can increase over hundreds to millions of years. The pulsar begins to emit X-rays, and the pair of objects is known as a "low-mass X-ray binary," Ransom said.

These cannibalistic pulsars have been called "black widow" pulsars or "redback" pulsars in reference to two species of spider that are known to kill their companions. Millisecond pulsars are the oldest known pulsars — some are billions of years old and will continue to spin at those high rates for billions of years. Follow Calla Cofield callacofield. 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. Neutron stars are formed when a massive star runs out of fuel and collapses. If the core of the collapsing star is between about 1 and 3 solar masses, these newly-created neutrons can stop the collapse, leaving behind a neutron star.

Stars with higher masses will continue to collapse into stellar-mass black holes. These stellar remnants measure about 20 kilometers Since neutron stars began their existence as stars, they are found scattered throughout the galaxy in the same places where we find stars.

And like stars, they can be found by themselves or in binary systems with a companion. Many neutron stars are likely undetectable because they simply do not emit enough radiation. However, under certain conditions, they can be easily observed. A handful of neutron stars have been found sitting at the centers of supernova remnants quietly emitting X-rays.