Scientists may have witnessed a massive, dying star split in two and then crash back together, triggering a never-before-seen double explosion. The explosion sent ripples through space-time and forged some of the universe's heaviest elements.
Most massive stars reach the ends of their lives by collapsing and exploding as supernovas, seeding the cosmos with elements such as carbon and iron. A different kind of cataclysm, known as a kilonova, occurs when the ultradense remnants of dead stars, called neutron stars, collide, forging even heavier elements like gold.
