About J1631-1612
J1631-1612 is an uncommon pulsar. It spins once every 677.684 ms, has a dispersion measure of 33.77 pc cm⁻³ and carries a surface magnetic field around 8.72×10^11 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.