A supernova explosion near the forming solar system could explain the presence of key radioactive elements that influenced Earth's water content. Researchers suggest this process occurred at a safe distance, avoiding disruption to planet formation. The mechanism implies Earth-like planets might be common around sun-like stars.
The solar system's formation may have been influenced by a supernova about 3 light years away, according to a study by Ryo Sawada at the University of Tokyo and his team. Ancient meteorite samples reveal that the early solar system contained short-lived radioactive elements, such as aluminium, manganese, beryllium, and calcium. These elements generated heat that expelled excess water from comets and space rocks, leaving Earth with the precise amount needed for life.
Previous models struggled to account for these elements' ratios without simulating catastrophic disruptions from nearby blasts. Sawada's model proposes a two-stage delivery: shock waves from the supernova carried direct ejecta like radioactive aluminium and manganese to the protoplanetary disk. Following these waves, cosmic rays bombarded atoms in the disk, producing beryllium and calcium isotopes.
"Previous models of solar system formation focused only on the injection of matter. I realised we were ignoring the high-energy particles," Sawada explained. "I thought, ‘What if the young solar system was simply engulfed in this particle bath?’"
This distant supernova scenario avoids the fragility issues of closer events, which Sawada likened to "winning the lottery." Instead, it suggests a common galactic process, potentially affecting 10 to 50 percent of sun-like stars and enabling Earth-like water abundances on their planets.
Cosimo Inserra at Cardiff University praised the balance in the model: "It’s quite novel, because it’s a fine balance between destruction and creation. You need the right elements and the right distance."
If validated, this could inform searches by telescopes like NASA's Habitable Worlds Observatory, targeting systems near ancient supernovae remnants for habitable worlds. The findings appear in Science Advances (DOI: 10.1126/sciadv.adx7892).