About J1739-3131
J1739-3131 is an uncommon pulsar. It spins once every 529.441 ms, has a dispersion measure of 596.9 pc cm⁻³ and carries a surface magnetic field around 3.17×10^12 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.