Kilonovae

A kilonova occurs when two neutron stars merge. Astronomical objects in a binary system are usually stable and do not fall into each other, but in the case of neutron star binaries, the intense gravitational effects of orbiting neutron stars radiate their gravitational bond off in the form of gravitational waves, in a mechanism known as gravitational decay. They eventually crash into each other and result in a rare event known as a kilonova. While they are more than a thousand times brighter than a classical nova, they are only about 1-10% as bright as a supernova and are not as easy to find.

Kilonova produces almost all of the extra-heavy and extra-rare elements in the Universe, such as gold, silver, and platinum. A merger between a neutron star and a black hole is also called a kilonova.