Scientists find 'smoking gun' proof of a recent supernova near Earth

A supernova exploded near Earth about 2.5 million years ago, possibly causing an extinction event.

Scientists find 'smoking gun' proof of a recent supernova near Earth

An artist's impression of a supernova.

Credit: NASA/ESA/G. Bacon, STScI
  • Researchers from the University of Munich find evidence of a supernova near Earth.
  • A star exploded close to our planet about 2.5 million years ago.
  • The scientists deduced this by finding unusual concentrations of isotopes, created by a supernova.

If you wanted some more shattering news, we now know that a supernova exploded very close to Earth about 2.5 million years ago. That might sound like a long time ago, but in the life of our 4.5 billion-year-old planet, that's just yesterday.

Supernovas are amazingly bright explosions of stars at the end of their lives. A recent study found a blast 4.5 million light-years away could release as much as 10 times the amount of energy that a sun can emit in its lifetime. It also spreads a tremendous amount of chemicals all throughout the cosmos. Just-released research looked at such a spread and found that concentrations of particular elements point to a supernova near Earth just 2.5 million years ago.

The scientists found an unusual amount of 53Mn, a radioisotope made by supernovas. Previous studies looked for such traces in concentrations of 60Fe, an isotope of iron.

The scientists, led by Dr. Gunther Korschinek from the Technical University of Munich, focused their study on ferromanganese crusts. These marine sediments, composed mainly of iron and manganese oxides, grow in time and jut out from the water. This makes them great record-keepers of chemicals in the water around them. While examining these ferromanganese crusts from locations in the Pacific Ocean, the team found not only the isotope 60Fe, but also 53Mn. The samples came from 1,589 meters (5,213 feet) down to 5,120 meters (3.18 miles) down.

What does the presence of 60Fe tell the researchers? It's half-life of 2.6 million years indicates that it was created in a nearby supernova explosion in relatively recently times. Otherwise, 60Fe would have decayed into nickel.

One other explanation for the presence of the isotope is its possible creation in the death throes of asymptotic giant branch (AGB) stars. But the presence of 53Mn, which cannot be produced by such stars, clearly points to supernovae as the origin, think the scientists.

manganese crust

This Manganese crust started to form about 20 million years ago. Growing layer by layer, it resulted in minerals precipitated out of seawater.

Elevated concentrations of 60 Fe and 56 Mn in layers from 2.5 million years ago hints at a nearby supernova explosion around that time. Credit: Dominik Koll/ TUM

"The increased concentrations of manganese-53 can be taken as the 'smoking gun' – the ultimate proof that this supernova really did take place," shared Dr. Korschinek in a press release.

The researchers used accelerator mass spectrometry to locate the 53Mn atoms in the crust that looks like hardened chocolate cake.

"This is investigative ultra-trace analysis," said Korschinek. "We are talking about merely a few atoms here." He explained further that the technique is also very useful in figuring out the sizes of the original stars, adding "accelerator mass spectrometry is so sensitive that it even allows us to calculate from our measurements that the star that exploded must have had around 11 to 25 times the size of the sun."

If there was a supernova in Earth's relatively recent history, what effect did it have on the planet? The scientists think it likely caused cosmic ray showers and affected the climate. It might have also caused a partial extinction event – the Pliocene marine megafauna extinction

Check out the study "Supernova-Produced 53Mn on Earth" in the journal Physical Review Letters.

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Astronomers find more than 100,000 "stellar nurseries"

Every star we can see, including our sun, was born in one of these violent clouds.

Credit: NASA / ESA via Getty Images
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This article was originally published on our sister site, Freethink.

An international team of astronomers has conducted the biggest survey of stellar nurseries to date, charting more than 100,000 star-birthing regions across our corner of the universe.

Stellar nurseries: Outer space is filled with clouds of dust and gas called nebulae. In some of these nebulae, gravity will pull the dust and gas into clumps that eventually get so big, they collapse on themselves — and a star is born.

These star-birthing nebulae are known as stellar nurseries.

The challenge: Stars are a key part of the universe — they lead to the formation of planets and produce the elements needed to create life as we know it. A better understanding of stars, then, means a better understanding of the universe — but there's still a lot we don't know about star formation.

This is partly because it's hard to see what's going on in stellar nurseries — the clouds of dust obscure optical telescopes' view — and also because there are just so many of them that it's hard to know what the average nursery is like.

The survey: The astronomers conducted their survey of stellar nurseries using the massive ALMA telescope array in Chile. Because ALMA is a radio telescope, it captures the radio waves emanating from celestial objects, rather than the light.

"The new thing ... is that we can use ALMA to take pictures of many galaxies, and these pictures are as sharp and detailed as those taken by optical telescopes," Jiayi Sun, an Ohio State University (OSU) researcher, said in a press release.

"This just hasn't been possible before."

Over the course of the five-year survey, the group was able to chart more than 100,000 stellar nurseries across more than 90 nearby galaxies, expanding the amount of available data on the celestial objects tenfold, according to OSU researcher Adam Leroy.

New insights: The survey is already yielding new insights into stellar nurseries, including the fact that they appear to be more diverse than previously thought.

"For a long time, conventional wisdom among astronomers was that all stellar nurseries looked more or less the same," Sun said. "But with this survey we can see that this is really not the case."

"While there are some similarities, the nature and appearance of these nurseries change within and among galaxies," he continued, "just like cities or trees may vary in important ways as you go from place to place across the world."

Astronomers have also learned from the survey that stellar nurseries aren't particularly efficient at producing stars and tend to live for only 10 to 30 million years, which isn't very long on a universal scale.

Looking ahead: Data from the survey is now publicly available, so expect to see other researchers using it to make their own observations about stellar nurseries in the future.

"We have an incredible dataset here that will continue to be useful," Leroy said. "This is really a new view of galaxies and we expect to be learning from it for years to come."

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  • The team at Clearspace, in collaboration with the European Space Agency, is on a mission to capture one such object using an autonomous spacecraft with claw-like arms. It's an expensive and very tricky mission, but one that could have a major impact on the future of space exploration.

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Catch more Just Might Work episodes on their channel:
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