About J1737-0314E
J1737-0314E is a rare pulsar. It spins once every 2.28 ms and has a dispersion measure of 80.4 pc cm⁻³.
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.