Neutron star

Neutron star, hypothetical extremely small star, of large mass but very great density. It is believed that when certain stars explode as supernovas their cores collapse and form either a neutron star or a collapsar (black hole). Neutron stars are thought to be made up of elementary particles and neutrons created from the compressed protons and electrons of the original supernova core, emitting powerful X-rays and reaching extremely high temperatures in the first few months of their existence. They may be more than 72,000 times smaller in diameter than the sun but with the same mass. In 1938 scientists predicted the existence of neutron stars, and in 1967 astronomers in Great Britain located pulsars—objects in space that emit radio waves, believed to be rotating neutron stars.

See also: Pulsar.