Binary systems made up of two massive objects orbiting each other are an important source for gravitational-wave astronomy. The system emits gravitational radiation as it orbits, these carry away energy and momentum, causing the orbit to shrink.[1][2] Shown here is a binary white dwarf system, an important source for space-borne detectors like eLISA. The eventual merger of the white dwarfs may result in a supernova, represented by the explosion in the third panel.