PIX4607586: Colliding neutron stars and gravitational waves - Colliding neutron stars and gravitational waves: Artist's view of two colliding neutron stars about to merge and explode in kilonova. This type of event produces gravitational waves and a gamma ray burst. This artist's impression shows two tiny but very dense neutron stars at the point at which they merge and explode as a kilonova. Such a very rare event is expected to produce both gravitational waves and a short gamma-ray burst, both of which were observed on 17 August 2017 by LIGO-Virgo and Fermi/INTEGRAL respectively. Subsequent detailed observations with many ESO telescopes confirmed that this object, seen in the galaxy NGC 4993 about 130 million light-years from the Earth, is indeed a kilonova. Such objects are the main source of very heavy chemical elements, such as gold and platinum, in the Universe / Bridgeman Images