Scientists have discovered radioactive stardust from ancient stellar explosions trapped in Antarctic ice. This exciting find sheds light on our solar system’s history.
Throughout space, vast clouds of gas and dust float between stars. One of these clouds, called the Local Interstellar Cloud or “Local Fluff,” is where our solar system is currently traveling. As Earth moves through this cloud, it picks up materials that can include remnants from supernovas, like a radioactive iron isotope known as iron-60 (60Fe).
In a recent study, lead researcher Dominik Koll pointed out that if 60Fe condenses into stardust, it can make its way to Earth. They detected this isotope in Antarctic snow back in 2019 but were unsure of its origin. Following further research, they traced it back to the Local Interstellar Cloud.
The team examined over 661 pounds (about 300 kilograms) of ancient ice, around 40,000 to 80,000 years old. They used a method called accelerator mass spectrometry to identify individual atoms of 60Fe in their samples. Their findings revealed less 60Fe in older ice compared to recent snow, suggesting that less interstellar dust reached Earth during that time. This points toward a shorter, more local source for the isotope rather than a distant explosion.
A stellar explosion within the Local Interstellar Cloud is likely the culprit for the iron-60 found. Koll noted, “This connects the clouds surrounding our solar system to a stellar explosion.” This discovery allows scientists to explore the origins of these cosmic clouds.
Interestingly, our solar system has been moving through the Local Interstellar Cloud for about 40,000 to 124,000 years. Future research is set to delve even further back in time, studying ice samples from periods before our solar system began its journey through this cloud.
This study was published on May 13 in the journal Physical Review Letters, offering a new understanding of the connections between stardust and our planet.
