About J1554-5209
J1554-5209 is an uncommon pulsar. It spins once every 125.23 ms, has a dispersion measure of 130.8 pc cm⁻³ and carries a surface magnetic field around 5.42×10^11 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.