Scientists link Pacific sediment anomaly to ancient supernova explosion

Chandra image shows Cassiopeia A, the youngest supernova remnant in the Milky Way. (Image: NASA)

An inexplicable spike of beryllium-10 was found in Pacific Ocean sediments by a team of international researchers which implies that a supernova explosion may have occurred nearby some 10 million years ago.

Beryllium-10 is a radioactive isotope and forms whenever cosmic rays hit Earth's atmosphere, meaning it can provide a cosmic fingerprint and clues to past astronomical happenings.

Leveraging data from the European Space Agency’s Gaia survey, scientists attempted to reconstruct how the Sun and neighbouring star clusters moved through space over the past 20 million years. This data shows there is a 68% chance that a supernova exploded within 326 light-years of Earth around the time of the beryllium-10 spike and possibly affected the cosmic environment of our planet.

The researchers identified 19-star clusters that had a chance of greater than 1% of having a supernova within this window of time. These star clusters could have contributed cosmic rays to our planet and formed chemical inoculations in the ocean sediments.

The researchers caution that, while we can hypothesis that a supernova explosion occurred, the spike may just relate to local Pacific Ocean conditions. Sediment burial or ocean currents may have changed fluxes of beryllium-10 in different ocean areas, suggesting the need for more extensive sampling to test a supernova hypothesis for the spike.

This discovery emphasise the effect of cosmic events on the environment and development of Earth. Recognising the prior occurrences of supernovae allows scientists to evaluate the effect of astronomical events on climate, radiation levels, and planetary history.

Future research will include sampling sediments from various oceans to validate the beryllium-10 spike is a global phenomenon and further determine the source of this ancient stellar explosion.