Abstract DGP2026-95

As Earth travels through the galaxy, it is exposed to cosmic particles from the surrounding interstellar medium. The identification of such cosmic material in geological archives provides evidence of past cosmic events, including nearby stellar explosions. In particular, the radionuclide Fe-60 has been detected in deep-sea sediments, polar ice, and lunar samples, indicating episodes of enhanced supernova (SN) activity in the vicinity of Earth approximately 2–3 and 7–8 million years ago, respectively - a discovery that has made important contributions to nuclear astrophysics in recent years.

These observational data corroborate theoretical models proposing that more than ten supernovae exploded at distances of approximately 50–150 pc over the past 10–15 million years. Their overriding shock fronts are thought to have generated an extended region of hot, low-density gas known as the “Local Bubble,” which can be seen in observational data and within which the Solar System is located.

In this project, we investigate terrestrial sedimentary archives for SN signatures for the first time, focusing on deposits from the Atacama Desert in Chile—the world’s oldest and driest desert. Unlike previously studied archives, sediments from the Atacama Desert are easily accessible, and more than 10 million years old. The region’s arid to hyper-arid climate further favors the preservation of cosmic material over millions of years. These characteristics make the Atacama Desert a promising archive for constraining the timing and frequency of nearby SNe and for laying the groundwork to evaluate their effects on Earth.