When two neutron stars collide, it doesn't go unnoticed. But for the first time, astronomers are providing a clear and detailed picture of such an event. And how gold is made from it!
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A neutron star corresponds to the final life stage of a massive star. It is an exceptionally dense object. As if all of humanity were concentrated in a cube of sugar. We know that the collision of two neutron stars creates some of the most extreme conditions in our universe. Conditions essential for the formation of heavy elements such as uranium or gold.
The scenario of a collision between neutron stars
In 2017, astronomers were able to detect signs of a collision between neutron stars for the first time. Gravitational waves, a gamma ray burst, all accompanied by a flash of light. Event GW170817 occurred about 130 million light-years from our Earth. And by combining all this data with results from laboratory experiments in a new modeling tool, researchers at the Max Planck Institute for Gravitational Physics and the University of Potsdam (Germany) have gained most of the details of what happened then. They published it in the journal Nature Communications.
Using the recorded gravitational waves, they first describe the final orbits of the two neutron stars. Trajectories that resulted in a collision that ejected heavy elements into space. Some of these radioactive elements then decayed into more stable elements like gold, raising the temperature and producing a barrage of electromagnetic signals ranging from infrared to ultraviolet to visible light. A gamma ray burst, also caused by the collision of neutron stars, ejected even more material. And the reaction of this material with the environment emits X-rays and radio waves.
Study other collisions to better understand how gold is formed
The improved gravitational wave detectors have started their fourth observation campaign. And astronomers hope they will reveal more neutron star collisions that could be studied with the tool they developed.