Overview
- Researchers report the radioactive isotope iron-60 in Antarctic ice, with far less in layers from 40,000–80,000 years ago than in today’s snow and recent seafloor sediment.
- The team links the higher modern levels to the Local Interstellar Cloud, a nearby gas-and-dust zone the solar system is crossing that they argue carries debris from ancient supernovae.
- They processed roughly 300 kilograms of Antarctic ice in Dresden and used accelerator mass spectrometry to isolate single iron-60 atoms from about 10 trillion other atoms.
- Iron-60’s 2.6 million-year half-life makes any atoms found on Earth a tracer of relatively recent supernova material rather than leftover matter from the solar system’s birth.
- Follow-up work will probe older ice cores and more sediments to pinpoint the cloud’s boundary and track how the influx changed, offering a new way to study interstellar dust without spacecraft.