Editing Nucleosynthesis (section)

===Neutron star mergers===
The [[Neutron star collision|merger]] of binary neutron stars (BNSs) is now believed to be the main source of r-process elements.<ref>{{cite web |last=Stromberg |first=Joseph |date=16 July 2013 |title=All the Gold in the Universe Could Come from the Collisions of Neutron Stars |url=http://www.smithsonianmag.com/science-nature/all-the-gold-in-the-universe-could-come-from-the-collisions-of-neutron-stars-13474145/?page=1 |work=[[Smithsonian (magazine)|Smithsonian]] |access-date=27 April 2014}}</ref> Being neutron-rich by definition, mergers of this type had been suspected of being a source of such elements, but definitive evidence was difficult to obtain. In 2017 strong evidence emerged, when [[LIGO]], [[Virgo interferometer|VIRGO]], the [[Fermi Gamma-ray Space Telescope]] and [[INTEGRAL]], along with a collaboration of many observatories around the world, detected both [[gravitational wave]] and electromagnetic signatures of a likely neutron star merger, [[GW170817]], and subsequently detected signals of numerous heavy elements such as gold as the ejected [[Degenerate matter#Neutron degeneracy|degenerate matter]] decays and cools.<ref>{{cite web |last=Chu |first=J. |date=n.d. |url=https://www.ligo.caltech.edu/page/press-release-gw170817 |title=GW170817 Press Release |publisher=[[LIGO]]/[[Caltech]] |access-date=2018-07-04}}</ref> The first detection of the merger of a neutron star and black hole (NSBHs) came in July 2021 and more after but analysis seem to favor BNSs over NSBHs as the main contributors to heavy metal production.<ref>{{Cite journal|last1=Chen|first1=Hsin-Yu|last2=Vitale|first2=Salvatore|last3=Foucart|first3=Francois|date=2021-10-01|title=The Relative Contribution to Heavy Metals Production from Binary Neutron Star Mergers and Neutron Star–Black Hole Mergers|journal=The Astrophysical Journal Letters|volume=920|issue=1|pages=L3|doi=10.3847/2041-8213/ac26c6|arxiv=2107.02714 |bibcode=2021ApJ...920L...3C |s2cid=238198587 |issn=2041-8205|doi-access=free}}</ref><ref>{{Cite web|title=Neutron star collisions are a "goldmine" of heavy elements, study finds|url=https://news.mit.edu/2021/neutron-star-collisions-goldmine-heavy-elements-1025|access-date=2021-12-23|website=MIT News {{!}} Massachusetts Institute of Technology|date=25 October 2021 |language=en}}</ref>