A supernova produces either a black hole or a very hot object called a neutron star. A neutron star is made almost entirely of neutrons. A neutron is an elementary particle, like a proton. But a neutron has no electrical charge. It is electrically neutral.
Models tell scientists that a supernova sends a star's outer layers into space.
The inner parts fall in on themselves, creating a neutron star. In a neutron star, an enormous amount of matter fills a very small space. But the material in a neutron star is not so densely packed as in a black hole. It is as if a giant trash compactor has squeezed the star. The material is so compact that one thimbleful of a neutron star has more matter than there is in 10 million elephants.