About J1838+1523
J1838+1523 is an uncommon pulsar. It spins once every 549.161 ms, has a dispersion measure of 68.26 pc cm⁻³ and carries a surface magnetic field around 1.07×10^11 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.