Interstellar ^{60}Fe in Antarctica

Area of Science:

• Cosmochemistry
• Astrophysics
• Nuclear Physics

Background:

• Earth accumulates extraterrestrial dust, offering clues to cosmic processes like stellar nucleosynthesis.
• Long-lived radionuclides in this dust can trace past astrophysical events.

Purpose of the Study:

• To report the first detection of recent iron-60 (⁶⁰Fe) influx to Earth.
• To investigate the origin of extraterrestrial radionuclides found in terrestrial samples.

Main Methods:

• Analysis of 500 kg of Antarctic snow using accelerator mass spectrometry.
• Measurement of cosmogenic radionuclide ⁵³Mn alongside ⁶⁰Fe.
• Elimination of terrestrial sources like global fallout.

Main Results:

• Detection of a ⁶⁰Fe/⁵³Mn atomic ratio of 0.017, significantly exceeding cosmogenic production levels.
• Exclusion of terrestrial origins for the detected ⁶⁰Fe excess.
• Attribution of the excess ⁶⁰Fe to interstellar sources.

Conclusions:

• This study provides the first evidence of a recent influx of interstellar ⁶⁰Fe onto Earth.
• The findings suggest the ⁶⁰Fe may originate from the solar neighborhood.
• This opens new avenues for studying recent cosmic events and material transfer.