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20 million-year-old stardust an amazing Antarctic find

Tuesday, August 20th 2019, 6:20 pm - Researchers studying the heavens sometimes rely on a source much closer to home.

Antarctic snow is a favourite when it comes to those studying the solar system and beyond. Its remote location and relatively untouched state make it a prime location for finding things like undisturbed meteorites and -- sometimes -- things much, much rarer.

In this case, stardust that may have first burst from a supernova some 20 million years ago.

Astronomers from Germany and Austria made the discovery after melting 500 kilograms of snow gathered from a high-altitude (and largely contaminant-free) part of the continent, then melting and analyzing the sample in the lab.

The result was a pleasant surprise for the team.

"I'm really glad and happy to actually see something which travelled billions of billions of kilometres through space and is millions of years old," Dominik Koll, a nuclear astrophysicist who led the discovery and co-authored the study, told CNN.

The 'something' in question was a rare isotope of iron -- iron-60 -- that the team believes came to settle on Antarctica sometime in the past 20 years, given that the sampled snow was less than 20 years old.

What makes researchers think this particular dust is interstellar? Iron-60 is unstable, so while it may have been present on Earth when the planet was new, it's long since decayed. It's also created, in small amounts, in nuclear reactors and explosions, but even events like the Fukushima power plant disaster didn't introduce enough to the environment for it to be measured.

That leaves just one source -- space dust produced by the explosion of a supernova somewhere in our solar neighbourhood.

Previously, researchers have found iron-60 in ocean sediments and from lunar samples -- presumably from supernovae long ago. "To be able to use the data on Earth that's pretty amazing," Koll told CNN. Finding a new -- seemingly more recent source -- could tell us more about the interstellar landscape around us.

"You learn quite a lot about the dynamics, about the solar neighbourhood," Koll said. "It means all our understanding about the process and dynamics, that it all fits together."

Sources: Physical Review Letters | APS Physics | CNN | LiveScience |


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