About J0137+1654
J0137+1654 is an uncommon pulsar. It spins once every 414.763 ms, has a dispersion measure of 26.08 pc cm⁻³ and carries a surface magnetic field around 7.21×10^10 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.