Partway through, the point-of-view changes so that we can see the beams of light sweeping across our line of sight this is how a pulsar pulses. The video below is an animation of a neutron star showing the magnetic field rotating with the star. Even though the light is constantly shining, you only see the beam when it is pointing directly in your direction. At night, a lighthouse emits a beam of light that sweeps across the sky. One way to think of a pulsar is like a lighthouse. 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.
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.
These accelerated particles produce very powerful beams of light. Pulsars have very strong magnetic fields which funnel jets of particles out along the two magnetic poles. Pulsars are rotating neutron stars observed to have pulses of radiation at very regular intervals that typically range from milliseconds to seconds. Most neutron stars are observed as pulsars. Below we introduce two general classes of non-quiet neutron star – pulsars and magnetars. In binary systems, some neutron stars can be found accreting materials from their companions, emitting electromagnetic radiation powered by the gravitational energy of the accreting material. More often, though, neutron stars are found spinning wildly with extreme magnetic fields as pulsars or magnetars. A handful of neutron stars have been found sitting at the centers of supernova remnants quietly emitting X-rays. However, under certain conditions, they can be easily observed. Many neutron stars are likely undetectable because they simply do not emit enough radiation. And like stars, they can be found by themselves or in binary systems with a companion. Since neutron stars began their existence as stars, they are found scattered throughout the galaxy in the same places where we find stars. (Credit: NASA/Goddard Space Flight Center Conceptual Image Lab) If that beam sweeps over Earth, we see it as a regular pulse of light. As the neutron star spins, the magnetic field spins with it, sweeping that beam through space. This diagram of a pulsar shows the neutron star with a strong magnetic field (field lines shown in blue) and a beam of light along the magnetic axis. One sugar cube of neutron star material would weigh about 1 trillion kilograms (or 1 billion tons) on Earth about as much as a mountain. These stellar remnants measure about 20 kilometers (12.5 miles) across. This collapse leaves behind the most dense object known an object with the mass of a sun squished down to the size of a city. (Stars with higher masses will continue to collapse into stellar-mass black holes.) 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. The very central region of the star the core collapses, crushing together every proton and electron into a neutron. Neutron stars are formed when a massive star runs out of fuel and collapses. (Credit: NASA's Goddard Space Flight Center) A neutron star is the densest object astronomers can observe directly, crushing half a million times Earth's mass into a sphere about 12 miles across, or similar in size to Manhattan Island, as shown in this illustration.
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