Remnants of Ancient Supernova Explosion found in Magnetotactic Bacteria

Back in 2004, German scientists discovered traces of supernova ejecta that had been deposited in the deep-sea ferromanganese crust of the pacific ocean. 

They dated the supernova event to 2.8 million years ago (Mya), using estimates from the decay of iron-60 radioisotope.

They were also able to estimate the distance of the supernova event to 10 parsecs (pc) from our sun, based on the amount of iron-60 deposited.

Prof Shawn Bishop

At the April 14th meeting of the American Physical Society (APS), another German scientist, Shawn Bishop, reported finding traces of iron-60 of supernova origin in the fossilized remains of a common bacteria.

By accurately dating the sediment cores in which the samples were found, Bishop appears to have discovered the first biological signature of an ancient supernova event, and may even be able to link it to a specific exploding star.

Bishop analyzed sample cores from strata roughly 100,000 years apart within deposits from 1.7 to 3.3 Mya. Iron-60 is not a product of any processes occurring here on earth, so any supply of it can be assumed to from a non-terrestrial source.

Bishop was able to extract out all the iron-60 of biological origin, and quantify it with a mass spectrometer.

The amounts found were small, but they were enough to reliably date the sample to a period around 2.2 Mya.

Other researchers, peripheral to the project, were then able to suggest a possible candidate star that dates to this period may lie in the Scorpius-Centaurus stellar association, roughly 130 pcs (424 light-years) from the sun.

More information: Abstract: X8.00002 : Search for Supernova 60Fe in the Earth's Fossil Record, Bulletin of the American Physical Society, meetings.aps.org/Meeting/APR13/Event/192798