Researchers from the University of Vienna have unveiled a groundbreaking discovery at the bottom of the Pacific Ocean, where they found an unusual concentration of Beryllium-10 (10Be). This discovery will soon be published in the scientific journal Astronomy & Astrophysics. It could provide insight into a large star explosion – called a supernova – that happened about 10 million years ago. The study, led by Efrem Maconi and his team, involved tracing the past orbits of the sun alongside 2,725 star clusters over a span of 20 million years.
To illustrate their work, the researchers identified two star clusters from within the Orion star-forming region. Of those, they ruled out those ASCC 20 and OCSN 61 as possible candidates for the supernova that would have produced the elevated levels of 10Be found. Their analysis revealed a significant correlation between the time of the 10Be spike and the likelihood of a massive star exploding nearby.
The Significance of Beryllium-10
Beryllium-10 is a relatively rare isotope, that usually only occurs when cosmic rays collide with Earth’s atmosphere or crust. Its unique occurrence in deep-sea sediments makes it an invaluable proxy for reconstructing past extreme Earth phenomena such as ocean warming, deoxygenation and acidification. Finding a significantly higher concentration of 10Be roughly 10 million years ago opens up questions about where that 10Be came from.
Dominik Koll, a researcher from Helmholtz-Zentrum Dresden-Rossendorf in Germany, was part of the team examining deep-ocean crusts for concentrations of this isotope. Koll and his colleagues set out to determine the age of these layers of rock, but were unprepared for what they discovered. The findings, published in the journal Nature Communications, indicate the Pacific Ocean is the only location on Earth that has this surplus of 10Be. The only potential alternative explanation is something terrestrial, such as changing ocean currents.
“Our results support the possibility of an SN (supernova) origin for the 10Be anomaly and highlight the importance of additional 10Be records from independent terrestrial archives to determine whether the anomaly is of astrophysical or terrestrial origin,” – scientists in their paper published in Astronomy & Astrophysics.
Tracing Star Clusters and Supernova Probabilities
Through sophisticated modeling techniques, the team was able to track the sun’s past orbit as well as that of several nearby star clusters. This work allowed them to identify target sites for future supernova activity. After processing the data, they found 19 previously unknown star clusters. From our calculations, each of these clusters has greater than 1% chance of producing at least one neighboring supernova within a 100 parsec distance over the time period associated with the increase in Beryllium-10 detections.
For these findings, we have found a very high likelihood. This leaves only a 32% probability that a very massive star exploded somewhere in this radius during the anomalous time. They indicated that the chance of such an event occurring much closer to Earth—around 35 parsecs (114 light-years)—is only about 1%. This information is critical for further understanding the dynamics between stellar explosions and their impacts on Earth’s geological and atmospheric conditions.
Implications for Future Research
The impacts of this finding go far deeper than just gaining insight into what happened in the past. It opens avenues for future research aimed at identifying and analyzing other terrestrial archives that may hold similar records of Beryllium-10. These results emphasize the need for more impactful, deep studies. These studies would ideally disentangle the effects of astrophysical influences from terrestrial processes that might be confounding isotope concentration changes.
As scientists continue to explore the depths of our oceans and unravel the mysteries they hold, this study underscores the interconnectedness of cosmic events and Earth’s geological history. The joint efforts of researchers from multiple institutions are shining an important light on the need for interdisciplinary work to advance our scientific understanding.