When a massive star exhausts its thermonuclear fuel, its core collapses and the outer layers are blown off in a colossal explosion — a supernova (a term coined by Fritz Zwicky while studying these catastrophes). What remains at the center is a neutron star — an object the size of a city but compressed to staggering density: a mass greater than the Sun packed into a sphere about 20 kilometers in diameter. This neutron star consists mostly of neutrons — particles with no electric charge. If such a remnant spins rapidly and has a strong magnetic field, it emits two narrow beams of radiation that sweep through space like a lighthouse beam. We see regular pulses: that's a pulsar.
A few years after the explosion of supernova SN 2012au in a distant spiral galaxy, astronomers detected a strengthening radio signal. A network of radio telescopes, combined via radio interferometry, worked like a giant ear, allowing precise measurement of the source's position. It turned out to be nearly stationary on the sky and very small in angular size. Its velocity, less than one-third of the speed of light, is typical for a young pulsar that just received a 'kick' from the explosion, not for ejecta slowing down in dust clouds of the interstellar medium.
If further observations confirm the object's nature, this would be the first radio pulsar discovered in another galaxy shortly after its birth. By studying its evolution, we could see how these cosmic lighthouses gain strength, slow their spin, and change their emission characteristics. Amazingly, the rotational energy of a pulsar is so stable that its pulse periods can rival the precision of atomic clocks, remaining unchanged even after millions of years — unless, of course, abrupt rearrangements occur in the neutron star's crust.
Some pulsars spin up to 700 times per second — faster than the crankshaft of a Formula 1 race car.