About 20 million years ago, some stars nearby went supernova, sending clouds of gas and dust into space. Today, our solar system is moving through what we call the Local Interstellar Cloud. Recent findings from Antarctica suggest that this cloud might be leaving traces of stardust on Earth.
In a fascinating study from 2019, a team led by Dominik Koll at the Australian National University collected around 1,100 pounds (500 kilograms) of snow from Antarctica. When they examined it, they found iron-60, a rare isotope linked to supernovae. After years of investigation, they concluded that this iron-60 likely came from the Local Interstellar Cloud and has been recorded in Antarctic snow for the past 80,000 years. These results were recently published in Physical Review Letters.
Koll mentioned in a column for The Conversation that while they found iron-60, it was less than expected. Still, it serves as an important marker of the cosmic cloud’s interaction with Earth’s geology.
Antarctica’s snow and ice provide a unique window into the past. According to Koll, the continent’s ice forms a nearly untouched record spanning tens of thousands of years, making it invaluable for geological studies.
Initially, scientists were divided on how iron-60 got into the Antarctic snow. While some thought it might be old material from ancient supernovae, others, including Koll’s team, believed the Local Interstellar Cloud could slowly deposit iron-60 onto Earth over time. This hypothesis required deep investigation.
The research process was meticulous. Scientists melted ice and treated it chemically to isolate tiny amounts of iron. They then used a particle accelerator to measure a few iron-60 atoms among trillions of particles.
The analysis showed surprisingly low iron-60 levels, which suggested less of the isotope reached Earth during the last 40,000 to 80,000 years. This raised new questions about the sources of this material. As Koll noted, it seemed more likely that the iron had come from a local source, rather than distant supernovae.
Interestingly, a recent study indicates that our solar system has been passing through the Local Interstellar Cloud for roughly 40,000 to 124,000 years, matching neatly with the new findings. It now appears that Antarctica has been capturing traces of stardust as our solar system moves through this cloud.
Despite the low levels of iron-60 found, these discoveries spark further curiosity. As Koll explained, understanding the origins and nature of the Local Interstellar Cloud is still an open question. Antarctic ice could play a crucial role in revealing the history and composition of this fascinating cosmic cloud.
“If we delve deeper into older ice,” Koll suggests, “we might unlock the secrets of these interstellar clouds, uncovering their full story and origins.”
Source link
Antarctica,Astrophysics,interstellar objects
