Scientists first proposed the existence of neutron stars in the 1930s

• A neutron star is a dense stellar corpse consisting primarily of closely packed degenerate neutrons

• A neutron star typically has a diameter of about 20 km, a mass less than 3 M_, a magnetic field 1012 times stronger than that of the Sun, and a rotation period of roughly 1 second

• Zwicky and Baade proposed that a highly compact ball of neutrons would produce a degenerate neutron pressure in star remnants too large to become white dwarfs

• Not verified until 1960’s