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A tiny grain of stardust — older than the solar system itself — sheds light on how planetary systems like ours form.

A microbe-sized particle — a graphite grain originating from a nova explosion which occurred over 4.5 billion years ago — has been liberated from a meteorite collected in Antartica by NASA.

The grain has been studied down to the atomic level by researchers from the University of Arizona and the University of Toronto. Jane Howe, an engineering professor at the latter institute explains: “This grain is presolar. It originated before the formation of the sun.

“It’s just amazing to analyze such an anomaly.”

A team of researchers found a grain of stardust (inset image) that survived the formation of our solar system and analyzed it with instruments sensitive enough to identify single atoms. Measuring one 25,000th of an inch, the carbon-rich graphite grain (red) revealed an embedded speck of oxygen-rich material (blue), two types of stardust that were thought could not form in the same nova eruption. (University of Arizona/Heather Roper)

The team of researchers used advanced ion and electron microscopes to observe the arrangement of carbon atoms and variations of these particles called carbon isotope anomalies — thus discovering a complete surprise. The presolar graphite grain contains oxygen-rich silicates.

This new observation gives fresh insight into the conditions in dying stars, as well as contradicting the currently favoured hypothesis that oxygen- and carbon-rich stardust materials — the buildings blocks of the next generation of stars and planets such as our solar system — couldn’t form together in the same nova explosion and under the same conditions.

Howe says: “Sometimes research is about satisfying your curiosity. One of the greatest curiosities is how the universe was formed and how life started.

“And this weirdo particle showed us something we didn’t know before.”



The future for this type of analysis

Howe now intends to expand her work using electron microscopy to study materials in the advancement of renewable energy sources to study meteoritic materials too.



Dr. Pierre Haenecour (left) of the Lunar and Planetary Laboratory at the University of Arizona and Professor Jane Howe (MSE, ChemE, at right), analyze images of stardust particles with Hitachi’s SU9000 low-voltage STEM/SEM electron microscope. (Photo courtesy of Maria Schuchardt, University of Arizona)

She says: “I thought this research project was really exciting, and I’m a curious person by nature. At the time, it was just part of my job assignment, but now it’s starting to become part of my research portfolio.”

Howe also hopes to expand collaborations with both the University of Arizona and University of Toronto professor Kim Tait in the department of Earth scientists. Tait also happens to be the senior curator of mineralogy at the Royal Ontario Museum which will allow Howe to study its collection of meteorites.

Howe will also be part of a Canadian team of researchers who study the samples returned from the carbon-rich asteroid Bennu when the NASA OSIRIS-Rex mission returns to Earth in 2023.

She concludes: “This kind of research, it’s part of a much larger debate of how life started on Earth. We all care about who we are and where we came from.

“I’m so excited to be part of advancing our knowledge in this.”

The international team, which including Howe, planetary scientists, astronomers and material scientists at UA, Washington University in St. Louis, Polytechnic University of Catalonia in Spain, and Hitachi High Technologies in the U.S. and Japan, have published their findings in Nature Astronomy.

Original research:

https://www.nature.com/articles/s41550-019-0757-4





















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