Searching for Contemporary Supernova Dust in Deep-Sea Sediments

The short-lived radioisotope 60Fe is synthesized predominantly in supernovae and is not produced efficiently by other mechanisms like cosmic-ray spallation. An excess of 60Fe has been detected in deep-sea sediments, ferromanganese crusts, and in Apollo 12 lunar soils. These measured excesses in 60Fe are consistent with an injection from a nearby supernova 2 Myr ago.

The solar wind and interplanetary magnetic field would have effectively shielded the Solar System from gas and plasma ejected from a nearby supernova, so it was likely supernova dust grains that carried the 60Fe signature to Earth and the Moon. Graphite and silicon-carbide dust grains from this supernova, phases that are well-studied in supernova grains that predated the formation of the Solar System, would have likely survived atmospheric entry. These grains would represent an extremely valuable sample of contemporary supernova dust that can be studied using high-precision laboratory techniques and compared to presolar (>4.6 Gyr old) supernova dust.

Here we describe our efforts to identify contemporary supernova dust in deep-sea sediments.