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mattbrowne's avatar

What do bacteria and supernova explosions have in common?

Asked by mattbrowne (31735points) May 10th, 2013

I find this story truly amazing. What are your thoughts? Can this approach revolutionize our study of supernovae and their history?

http://www.nature.com/news/supernova-left-its-mark-in-ancient-bacteria-1.12797

“Sediment in a deep-sea core may hold radioactive iron spewed by a distant supernova 2.2 million years ago and preserved in the fossilized remains of iron-loving bacteria. If confirmed, the iron traces would be the first biological signature of a specific exploding star. Shawn Bishop, a physicist at the Technical University of Munich in Germany, reported preliminary findings on 14 April at a meeting of the American Physical Society in Denver, Colorado.

In 2004, scientists reported finding the isotope iron-60, which does not form on Earth, in a piece of sea floor from the Pacific Ocean. They calculated how long ago this radioactive isotope had arrived by using the rate at which it decays over time. The culprit, they concluded, was a supernova in the cosmic neighborhood. Bishop wondered if he could find signs of that explosion in the fossil record on Earth. Some natural candidates are certain species of bacteria that gather iron from their environment to create 100-nanometre-wide magnetic crystals, which the microbes use to orient themselves within Earth’s magnetic field so that they can navigate to their preferred conditions. These ‘magnetotactic’ bacteria live in sea-floor sediments.

So Bishop and his colleagues acquired parts of a sediment core from the eastern equatorial Pacific Ocean, dating to between about 1.7 million and 3.3 million years ago. They took sediment samples from strata corresponding to periods roughly 100,000 years apart, and treated them with a chemical technique that extracts iron-60 but not iron from nonbiological sources, such as soil washing off the continents. The scientists then ran the samples through a mass spectrometer to see if any iron-60 was present. And it was. “It looks like there’s something there,” Bishop told reporters at the Denver meeting. The levels of iron-60 are minuscule, but the only place they seem to appear is in layers dated to around 2.2 million years ago. This apparent signal of iron-60, Bishop said, could be the remains of magnetite (Fe3O4) chains formed by bacteria on the sea floor as radioactive supernova debris showered on them from the atmosphere, after crossing inter-stellar space at nearly the speed of light. No one is sure what particular star might have exploded at this time, although one paper points to suspects in the Scorpius–Centaurus stellar association, at a distance of about 130 parsecs (424 light years) from the Sun.”

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7 Answers

josie's avatar

It would be even more interesting to do a similar analysis on each one of us and find out what cosmic event we were “related” to.
Thus making us true “Children of the Stars”.
A sort of legitimate astrology.

mattbrowne's avatar

You mean looking for iron isotopes in our hemoglobin molecules?

ucme's avatar

I think…erm, yeah, it’s like…err…oh shit, i’m out my depth here aren’t I?
I had a crumb on my tablet just then & accidentally gave you a GQ when I brushed it off the screen, an actual true event.

marinelife's avatar

As Mr. Spock said, “Fascinating!”

ETpro's avatar

@josie We are indeed children of the stars.

In answer to @mattbrowne‘s question, everything. None of the heavier elements necessary for life, or even for planetary formation, would exist if it were not for supernovae. When the Universe formed, there were only Hydrogen and Helium. No other elements on our current periodic chart existed till gravity bound enough of the two lightest elements together to form relatively massive stars, big enough to supernova when they had consumed their nuclear fuel. It is in the crucible of immense heat and pressure such massive stars undergo upon gravitational collapse that all the heavy elements are formed and blasted into space as dust clouds that then form new stars complete with planetary systems, and eventually life. So we are truly all children of the stars. Take the weekend off and celebrate now that you know that.

nebule's avatar

I have no idea @mattbrowne but I am still unbelievably in awe of your knowledge and philosophical perusings

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