Science

'Dust' from a star that exploded millions of years ago has been found in Antarctic snow


Incredibly rare ‘dust’ from a star that exploded millions of years ago has been found in Antarctic snow

  • Researchers say there is no chance the iron-60 isotope was made by humans
  • They suggest that a rock containing the material must have impacted the Earth 
  • This would have scattered the stardust, which then fell to the ground as snow
  • The dust was created when a nearby star exploded millions of years ago

Stardust found in freshly melted snow from Antarctica by Australian scientists contains a large amount of a rare isotope not found on Earth.

Experts say that there is no chance that the iron-60 isotope was made by humans, suggesting instead that it was delivered to Earth by an impact with a space rock. 

Iron-60 has four more neutrons than iron and can be found in the Earth’s crust but is not normally found in our atmosphere.

Scientists suggest that a rock containing the material, from  a star that exploded millions of years ago, must have impacted the Earth’s atmosphere.

This would have scattered the stardust, which then fell to the ground when captured in flakes of snow. 

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Stardust found in freshly melted snow from Antarctica by Australian scientists contains a large amount of a rare isotope not found on Earth

Stardust found in freshly melted snow from Antarctica by Australian scientists contains a large amount of a rare isotope not found on Earth 

‘Making these measurements is very difficult,’ Bernhard Peucker-Ehrenbrink, a geochemist at Woods Hole Oceanographic Institution, said in a press release. ‘You’re essentially counting individual atoms.’ 

Researchers melted about 1,100 pounds of snow from Antarctica, examining what was left behind.

They ruled out the creation of iron-60 from nuclear power plants and weapons tests, finding only a small amount could make it to the South Pole.

They also studied other isotopes to rule out iron-60 generated by cosmic rays after interacting with dust or meteorites.

Interstellar meteorites are rare, according to Avi Loeb, an astronomer at Harvard, but ‘the smaller the object size is, the more abundant it is.’

With this in mind, researchers say the source of iron-60 must be a supernova.

‘Not so near as to kill us, but not too far to be diluted in space,’ said lead researcher Dominik Koll, a physicist at Australian National University. 

Experts say that there is no chance that the iron-60 isotope was made by humans, suggesting instead that it was delivered to Earth by an impact with a space rock

Experts say that there is no chance that the iron-60 isotope was made by humans, suggesting instead that it was delivered to Earth by an impact with a space rock 

Dr Koll said that, in this case, the particles may have been picked up as Earth travels through the Local Interstellar Medium (ISM), a 30-light-year wide region of space that our solar system is currently passing through.

Spectacular displays of this interstellar medium can be found in star-forming regions where new stars are being created.

Planetary nebulae and supernova remnants where old stars are returning much of their mass back into space also 

In the region just around the sun, within approximately 100 parsecs, which is home to the local interstellar medium. 

Here we find a suite of warm, modest density, partially ionised clouds.More research is necessary to understand where and when the iron-60 got to Earth

It has a half-life of 2.6 million years – which Dr Koll said will require more data and ice cores that go deeper into the planet, reaching older dust.

The full findings of the study were published in the journal Physical Review Letters.

Iron-60 has four more neutrons than iron and can be found in the Earth's crust but is not normally found in our atmosphere. Pictured: Artist's impression of Antarctica from space

Iron-60 has four more neutrons than iron and can be found in the Earth’s crust but is not normally found in our atmosphere. Pictured: Artist’s impression of Antarctica from space

WHAT ARE THE DIFFERENT TYPES OF SPACE ROCKS?

An asteroid is a large chunk of rock left over from collisions or the early solar system. Most are located between Mars and Jupiter in the Main Belt.

A comet is a rock covered in ice, methane and other compounds. Their orbits take them much further out of the solar system.

A meteor is what astronomers call a flash of light in the atmosphere when debris burns up.

This debris itself is known as a meteoroid. Most are so small they are vapourised in the atmosphere.

If any of this meteoroid makes it to Earth, it is called a meteorite.

Meteors, meteoroids and meteorites normally originate from asteroids and comets.

For example, if Earth passes through the tail of a comet, much of the debris burns up in the atmosphere, forming a meteor shower.



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