About J1552+5437
J1552+5437 is a rare pulsar. It spins once every 2.428 ms, has a dispersion measure of 22.9 pc cm⁻³ and carries a surface magnetic field around 83,398,252 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.