Neutron Star

 

A neutron star is a dead star, about 1.5 times the mass of our sun concentrated in an area as small as a city.

How do they form? 

When a red giant has run out of fuel, it cools off and the pressure drops. This pressure change makes it collapse unto itself, which sends enormous shock waves and creates a spectacular explosion known as a supernova. The supernova compresses the core of the star so much that each electron and proton are merged and fused together forming "neutrons". 

The compressed core is as big as a city but so dense in mass that it weighs around 1.5 times the sun. And because it is made of neutrons, it has no electrical charge.

In future posts, we'll see how a neutron star can become a pulsar or a magnetar, and how it helps us to see the back of a star through gravitational lensing.