About J2015+0756
J2015+0756 is an epic pulsar. It spins once every 4.328 ms, has a dispersion measure of 36.44 pc cm⁻³ and carries a surface magnetic field around 171,910,911 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.