Astrophysics: microbes could carry traces a stellar explosion in it - Times Online

The particle of a dying star could have hit the Earth 2.2 million years ago. Researchers have discovered the first evidence of the collision in bacteria.

© NASA / JPL-Caltech / Steward / Krause et al.

remnants of a supernova in the constellation Cassiopeia in about 11,000 light years away

2.2 million years ago, when the first early humans lived in Africa today, exploded near the earth a star – at least that is a theory. The gigantic blast is said to have hurled a stream of billions of particles on our planet. The astrophysicist Shawn Bishop and his colleagues could be the first to show that such a supernova once shone in our cosmic neighborhood. In the fossilized relics iron loving bacteria they could be pushed to the residues of the starburst.

“There is something that is quite obvious,” said Bishop, who teaches at the Technical University of Munich. In microbes, the researchers found the radioactive iron isotope Fe-60th Such rare nuclei occur almost exclusively when a star reaches the end of its life, and bursting. Normally, Fe-60 no longer exist on Earth. It would be long decay. The half-life of 2.62 million years is too short to come from the origins of our more than four billion year old solar system. The scuffled probably once by the blast of a supernova of gas and dust together.

display

earthly traces of a supernova would be a sensation. It is still not clear whether cosmic catastrophes have influenced the evolution of living beings. Gamma, X-rays and cosmic rays of a star dust shock wave should have the ozone layer was severely affected. This UV light passes freely to the ground, micro-organisms can take up directly into the DNA damage.

fossil bacteria with the supernova iron core samples taken from the scientists from the floor of the Pacific had raised from a depth of nearly 4,000 meters. Already discovered in 2004 by Bishop colleagues in these same sediments Fe-60 atoms. But not in microbes and in such small quantity that proof was hard to prove.

probability of 95 percent

The Bishop brought the idea into the cores to fahnden magnetotactic bacteria for the remains. The iron-loving organisms living on the seabed and are in their cells crystals of magnetite ago, a compound of iron and oxygen (Fe3O4). The iron that process the microbes, the dust passes through the atmosphere into the oceans. The bacteria accumulate it to align so that the Earth’s magnetic field. So if a supernova remnant can be found on earth, in the form of fossilized microbes in Fe-60th

fact, the chemical analysis of a deep-sea core sample could have confirmed the thesis Bishops. This show results achieved by the researchers using an accelerator spectrometer after they solved the magnetite from the bacteria. “With a statistical probability of 95 percent, we were able to demonstrate Fe-60,” says Bishop. “As a risk-averse person, I’d say there’s something.”