Pulsars

What are pulsars? Pulsars are flickering stars. No this is not correct. Pulsars are not stars, indeed they are dead stars and they do not actually flicker or pulse.

Pulsars are neutron stars which radiates two steady narrow beam of electromagnetic radiations (light, radiowave, etc.) in opposite directions. Neutron stars form when a star more massive than the sun runs out of fuel in its core and collapses in on itself(Neutron stars will be explained in future posts). 

Neutron stars are typically about 20 to 24 km in diameter, but they can contain up to twice the mass of the sun, which is about 1.392 million km in diameter. A sugar-cube-size bit of material from a neutron star would weigh about 1 billion tons — "about the same as Mount Everest," according to NASA. The only object with a higher density than a neutron star is a black hole. Pulsars are highly magnetic. Pulsars have magnetic fields that range from 100 million times to 1 quadrillion (a million billion) times stronger than Earth's.

Why do pulsars seem to flicker? The reason is quite simple. It's similar to why a lighthouse seem to flicker. The axis of rotation of pulsar and the line in which light beams come out are at an angle. So as the pulsar spins, these light rays starts falling on earth then vanishes and then again appear, because of this phenomenon pulsars seem to flicker.

Why do pulsars spin? Because pulsars are formed from stars and we know that stars spin on their axis. Why pulsars spins faster than stars? Pulsars are neutron stars which form when stars collapses. When a star collapses its radius decreases so the whole mass gets concentrated near the axis of rotation and now to conserve the angular momentum, the neutron star's angular velocity increases. That's why pulsars spin so fast about hundreds of time pr second.

Why pulsars radiate? There is no correct explanation for it yet. But there is a theory why it radiates light. The theory goes like this- Pulsars are highly magnetic and a spinning magnetic field generates an electric field, which, in turn, can cause charged particles to move. At the poles where magnetic fields dominates the surface, 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, they radiate light. Why pulsars radiate radiowaves and gamma-rays? The answer to this question is still unknown.