A team of German scientists based out of the Technical University of Munich recently began a survey of ocean floor composition to study magnetotactic bacteria. These bacteria orient around magnetic fields and can absorb metals such as iron, allowing a window into the mysterious world of Earth’s magnetic fields.
In a surprising find, these scientists’ recent research published in Proceedings of the National Academy of Sciences has shown that several ocean floor samples taken from deep beneath the Pacific Ocean contain the isotope iron-60 (60Fe), a form of iron not commonly found on Earth.
According to this recently published data, the presence of iron-60 implies that some violent cosmic event, such as a supernova or meteor impact, deposited the rare metals across our cosmic neighborhood:
This radioisotope has no natural, terrestrial production mechanisms; thus, a detection of 60Fe atoms within terrestrial reservoirs is proof for the direct deposition of supernova material within our solar system.
Some of the samples contained just a few atoms of iron-60, while others had entire clusters of molecules. Due to the fact that the iron-60 was found near evidence of certain hydroxide molecules, researchers believe the isotope came to Earth via a nearby supernova; iron from meteorites tends to be found in other molecules such as magnetite or silicate, which were not present in these samples.
According to a press release issued by the Technical University of Munich, the iron-60 likely came from the Scorpius-Centaurus Association, one of the closest groups of stars to our Sun. Several supernovae have occurred in this stellar cluster in recent cosmic history, blasting matter outward and creating a small void in space:
Over the course of the last 10 to 15 million years, a succession of 15 to 20 supernovae has occurred in this star association. This series of massive stellar explosions has produced a largely matter-free cavity in the interstellar medium of a galactic arm of the Milky Way. Astronomers call this cavity, in which our solar system is located, the Local Bubble.
The magnetotactic bacteria used in this study have become a hot topic of research. Because these bacteria orient around magnetic fields and can absorb metals such as iron, they are an invaluable source of data about the history and current state of Earth’s magnetic field. After taking samples of soil or ocean floor sludge, scientists can study the fossilized remains of these ancient bacteria to study shifts in magnetic fields or the ancient geologic composition of soils.