Overview
- An HZDR‑led team reports in Physical Review Letters that an Antarctic ice core spanning 40,000 to 80,000 years holds fewer iron‑60 atoms than modern snow, showing the influx rose in recent times.
- The researchers say this pattern matches the solar system entering the Local Interstellar Cloud tens of thousands of years ago and moving near its edge today.
- Iron‑60 forms only in massive stars and is spread by supernovae, and its 2.6‑million‑year half‑life makes any detection on Earth a clear sign of extraterrestrial fallout.
- The team argues lingering dust from million‑year‑old nearby blasts is unlikely because the iron‑60 signal changed over only tens of thousands of years.
- Detecting the trace required isolating a few hundred milligrams of dust from about 300 kilograms of Antarctic ice and counting iron‑60 at ANU’s Heavy Ion Accelerator Facility, and the group will next test older Beyond EPICA cores to fix the entry time into the cloud.