About J1649-4653
J1649-4653 is an uncommon pulsar. It spins once every 557.036 ms, has a dispersion measure of 331 pc cm⁻³ and carries a surface magnetic field around 5.32×10^12 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.