Merging neutron stars, illustration - stock illustration

Neutron stars merging, illustration. Neutron stars are the remnants of stars that have run out of fuel and exploded as supernova, eventually collapsing into a superdense core. A typical neutron star has a mass of between 1.3 and 2.1 solar masses but measures only 10km in diameter. Neutron stars can exist as paired, or binary, stars. Seen here is the very final stage, just before full merger. This causes a violent burst of magnetic radiation lasting milliseconds. It is suggested that this is the source of short gamma ray bursts.