The universe is a giant cosmic kitchen, where chemical elements are “cooked” inside stars and in epic collisions. The heaviest ones, like gold and platinum, need the most extreme conditions. Astronomers thought the only “chefs” for these delicacies were neutron star mergers — the ultra-dense remnants of dead stars. But when scientists weighed all the gold in the Milky Way and compared it to the “output” of such mergers, they found a shortfall — a serious one.

They checked every known recipe. They even considered especially fast neutron star mergers and pairs of black holes and neutron stars, which also produce heavy elements. They added data from gravitational wave detectors, ripples in spacetime, along with spectroscopic observations (analyzing stars’ chemical makeup from their light) and powerful gamma-ray bursts. But even then the “dish” doesn’t add up: there should be way more precious metals.

That means another, still unidentified “cook” is at work in the cosmic kitchen. Maybe it’s a rare type of supernova explosion — a magnetar-powered hypernova, where matter is compressed and heated to unimaginable temperatures. Or the source might be hiding in collisions of even more exotic objects. The gold mystery remains unsolved, and astro-detectives keep hunting for the hidden ingredient.