About J1756-2225
J1756-2225 is an uncommon pulsar. It spins once every 404.98 ms, has a dispersion measure of 329 pc cm⁻³ and carries a surface magnetic field around 4.67×10^12 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.