About J1955+5059
J1955+5059 is an uncommon pulsar. It spins once every 518.938 ms, has a dispersion measure of 31.98 pc cm⁻³ and carries a surface magnetic field around 8.54×10^11 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.