Scientists have detected traces of iron-60 in Antarctic ice up to 80,000 years old, showing that the solar system is moving through material from an ancient stellar explosion. The findings come from a study published in Physical Review Letters and point to the Local Interstellar Cloud as the source of the radioactive isotope.
An international team from the Helmholtz-Zentrum Dresden-Rossendorf led the analysis of ice cores collected through the European EPICA project. The samples, formed between 40,000 and 80,000 years ago, contained lower levels of iron-60 than more recent measurements. This isotope forms only in supernova explosions and had previously been found in younger snow and sediments, leaving its origin unclear until now.