Meteorite contains the oldest material on Earth: 7-billion-year-old stardust

  • Meteorite contains the oldest material on Earth: 7-billion-year-old stardust

Meteorite contains the oldest material on Earth: 7-billion-year-old stardust

In this latest research, a team of researchers led by the cosmochemist Philipp Heck of the Field Museum in Chicago analyzed 50 presolar grains containing a mineral called silicon carbide.

That makes this stardust is the oldest material from the solar system ever found on Earth. But a number of the continuing to be particles tend to be another 700 million many years older. They're born when bits of dust and gas floating through space find each other and collapse in on each other and heat up. In turn, this helps the birth of new stars, creating a chain of space daisies.

Such "presolar grains" are tiny and rare, only found in about 5% of meteorites that have fallen to Earth.

A meteorite that fell straight down in 1969 nearby the Australian village of Murchison seems to include particles which can be a billion many years over the age of our solar power system.

A new study of the presolar grains of the Murchison meteorite recovered in Australia was published Monday in the Proceedings of the journal National Academy of Sciences.

"Despite having worked on the Murchison meteorite and presolar grains for nearly 20 years, I still am fascinated that we can study the history of our galaxy with a rock", Mr.

"They're solid samples of stars, real stardust". As the stars reached advanced stages of their evolution, the grains would have condensed into outflows and blown out into space, later to be taken up and incorporated into what would become the Murchison meteorite.

"It starts with crushing fragments of the meteorite down into a powder", Jennika Greer, a co-author of the study, said in a press release. "Once all the pieces are separated, it's a kind of dough, and it has a pungent characteristic". Then the crushed meteorite gets dissolved with acid until only the presolar grains remain.

They also measured the exposure of the grains to cosmic rays, highly energised particles zipping through our galaxy.

Some of these rays interact with the matter they encounter and form new elements.

Think of it this way: Imagine putting a bucket outside during a rainstorm. "Assuming the rainfall is constant, the amount of water that accumulates in the bucket tells you how long it was exposed", said Dr Heck.

Some of those presolar materials-microscopic grains that formed before the sun, measuring about 2 to 30 micrometers across-have been dated at 4.6 to 4.9 billion years old.

"But thanks to these grains, we now have direct evidence for a period of enhanced star formation in our galaxy 7 billion years ago with samples from meteorites".

"There is a large uncertainty because there is a lot of modeling involved in determining those ages", says Pierre Haenecour, an assistant professor with the University of Arizona's Lunar and Planetary Laboratory who studies meteorites and interstellar dust grains but was not involved in the new study. "Our hypothesis is that the majority of those grains, which are 4.9 to 4.6 billion years old, formed in an episode of enhanced star formation. There was a time before the solar system started when more stars formed than normal". Some think it is stable and immutable, while others think that there are peaks and troughs. This is one of the main conclusions of our study.

The researchers also learned that pre-solar grains often float through space stuck together in large clusters, like granola.

Understanding the grains illuminated not only the stars and the duration of their star dust, but also a better understanding of the galaxies and their chronology. "With this study, we have directly determined the lifetimes of stardust. We hope this will be picked up and studied so that people can use this as input for models of the whole galactic life cycle", he said.

"I'm still excited about just the idea of having a rock, taking a rock out of a cabinet, extracting minerals and learning something about the history of our galaxy", he said.

Scientists analysing a meteorite have discovered the oldest material known to exist on Earth.

When small to medium stars (from about 0.5 to 5 times the mass of the Sun) approach the ends of their lives, they expand into red giant stars and blow off their outer layers.