Washington: Researchers of the Cluster of Excellence Origin and Structure of the Universe at the Technische Universitaet Muenchen (TUM), found a radioactive iron isotope in fossil remnants of iron-loving bacteria, which they trace back to a supernova in our cosmic neighborhood.
This is the first proven biological signature of a starburst on our earth.
The age determination of the deep-drill core from the Pacific Ocean showed that the supernova must have occurred about 2.2 million years ago, roughly around the time when the modern human developed.
Most of the chemical elements have their origin in core collapse supernovae. When a star ends its life in a gigantic starburst, it throws most of its mass into space. The radioactive iron isotope Fe-60 is produced almost exclusively in such supernovae.
Because its half-life of 2.62 million years is short compared to the age of our solar system, no supernova iron should be present on Earth. Therefore, any discovery of Fe-60 on Earth would indicate a supernova in our cosmic neighborhood.
In the year 2004 scientists at TU Muenchen discovered Fe-60 on Earth for the first time in a ferromanganese crust obtained from the floor of the equatorial Pacific Ocean. Its geological dating puts the event around 2.2 million years ago.