Since the big bang, the early universe had hydrogen, helium, and a scant amount of lithium. Later, some heavier elements, including iron, were forged in stars. But one of the biggest mysteries in astrophysics is: How did the first elements heavier than iron, such as gold, get created and distributed throughout the universe?

“It’s a pretty fundamental question in terms of the origin of complex matter in the universe,” said Anirudh Patel, a doctoral student at Columbia University in New York. “It’s a fun puzzle that hasn’t actually been solved.”

Patel led a study using 20-year-old archival data from NASA and ESA telescopes that finds evidence for a surprising source of a large amount of these heavy elements: flares from highly magnetized neutron stars, called magnetars. The study is published in The Astrophysical Journal Letters.

Study authors estimate that magnetar giant flares could contribute up to 10% of the total abundance of elements heavier than iron in the galaxy. Since magnetars existed relatively early in the history of the universe, the first gold could have been made this way.