Sound Science Bite: March 12. Thar's Gold in Them Thar Neutron Stars!

Gravitational wave detectors (in Washington state, Italy, and Louisiana) have shown their mojo when it comes to increasing our understanding of the universe. On 17 Aug 2017 gravitational waves were detected indicating the merger of two neutron stars. Astronomical observatories across the world turned to examine the event. Neutron stars consist of, naturally, neutrons. A neutron under the right conditions can turn into a proton and an electron, which then might become a hydrogen atom. However, theory indicates neutron star mergers can produce much heavier atoms resulting from the tremendous explosion involved in the merger.

Hydrogen, helium, and some lithium formed during the big bang. Other common elements are formed in the interior of stars. Low-mass stars like the Sun expel elements into space as nebular material when they run out of nuclear fuel and become what is called a planetary nebula surrounding a white dwarf star. Supernova explosions eject heavier common atoms, such as carbon, oxygen, and iron, but are not strong enough to produce the really heavy elements such as gold and platinum. From analysis of the remant material of the merging neutron stars (the resulting object itself collapsed into a black hole), it was concluded about 10,000 Earth masses of heavy elements, including the precious metals gold and platinum, were created by the merger. Perhaps half of all elements in the universe heavier than iron were created in these mergers. However, don't get in a rush to go prospecting at the site of the merger. It occurred 130 million years ago and is therefore 130 million light years away.

The graviational wave observatory data allowed scientists to determine a much sought-after figure: the largest mass a neutron star can have before it collapses into a black hole. That number was 2.2 solar masses. As Laura Cadonati, associate professor at the School of Physics at Georgia Institute of technology was quoted as saying, "So welcome to the new era of gravitational wave cosmology." Gravitational observatories are now another tool in the astronomer's toolbox.