Identification of strontium in the merger of two neutron stars

Understand

Half of all the elements in the universe heavier than iron were created by rapid neutron capture.

• The theory for this astrophysical `$r$-process' was worked out six decades ago and requires an enormous neutron flux to make the bulk of these elements.
• Where this happens is still debated.
• A key piece of missing evidence is the identification of freshly-synthesised $r$-process elements in an astrophysical site.