About J2216+5759
J2216+5759 is an uncommon pulsar. It spins once every 419.102 ms, has a dispersion measure of 176 pc cm⁻³ and carries a surface magnetic field around 5.44×10^12 G.
The collapsed core of a star that exploded: about one and a half Suns of matter crushed into a ball the size of a city, held up only by the refusal of neutrons to be squeezed further.