Seven-billion-year-old stardust in meteorite ‘oldest solid material found’

Scanning electron microscope image of the 6.2-billion-year-old grain of silicon carbide from the Murchison meteorite. Image credit Heck et al doi 10.1073/pnas.1904573117

The Oldest Known Material on Earth Is Officially Older Than The Solar System

Eventually, these grains were carried to Earth in a meteorite.

Based on how many cosmic rays they had soaked up, most of the grains had to be 4.6 to 4.9 billion years old, and some grains were older than 5.5 billion years.

A team of researchers from the United States and Switzerland analysed 40 pre-solar grains contained in a portion of the Murchison meteorite, that fell in Australia in 1969. "This is one of the key findings of our study", said Dr Heck. It's even older than our Earth and the Sun, which are 4.5 and 4.6 billion years old respectively.

Another meteorite that was recently added to the Field Museum's collection, the Aguas Zarcas from Costa Rica, or "cosmic mudball meteorite", was said to smell like cooked Brussels sprouts.

Some of the pre-solar grains turned out to be the oldest ever discovered. The majority, about 60 percent, predated the solar system by 300 million years or fewer, according to the study.

"These are the oldest solid materials ever found, and they tell us about how stars formed in our Galaxy", said Dr. Philipp Heck, a curator at the Field Museum of Natural History and a researcher in the Chicago Center for Cosmochemistry and the Department of the Geophysical Sciences at the University of Chicago.

A meteorite that crash landed near Melbourne fifty years ago was carrying space dust older than the solar system itself, new research suggests. Then the crushed meteorite gets dissolved with acid until only the presolar grains remain. He describes the method as "burning down the haystack to find the needle", and while some presolar material is lost in the process, the technique has yielded tens of thousands of presolar grains, but only about 100 "large ones". The new study is evidence of the latter. To date the tiny amount of material, the researchers looked for the abundance of certain atoms formed by cosmic rays hitting the dust grains.

Once the presolar grains were isolated, the team figured out from what types of stars they came and how old they were.

Some of these rays interact with the matter they encounter and form new elements. Many of them had tales to tell about the meteorite's distinctive aroma.

Instead the researchers measured how long the grains have been exposed to the cosmic rays shooting through the universe. "The silicon can be split into helium and neon", Heck says.

Scientists have developed a method to determine stardust's age.

The stardust represented time capsules dating to before the solar system.

The authors acknowledge that their methodology, which uses neon isotopes to age grains, "suffers from relatively large uncertainties".

The grains are small, measuring from 2 to 30 micrometers in size.

Exposure age data allowed the researchers to measure their exposure to cosmic ray. I compare that to putting a bucket in a rainstorm. The more neon 21 includes such a particle, the longer it was subjected to cosmic rays in addition to older it really is.

Over time, the material in these planetary nebulae cools and condenses into grains of dust and minerals.

"We have more young beans than we expected", said Heck. But a number of the continuing to be particles tend to be another 700 million many years older.

As for the oldest grain, Haenecour says, "I think it is hard to really actually know that this grain is 7 billion years old", but adds that it does appear to be much older than the other grains in the study.

Stars are born when dust and gas floating through space find each other, collapse in on each other and heat up. The star dust found on the meteorite is called presolars because they formed before our sun. Billions of years later, a chunk of that asteroid crashed into Australia. This tends to make these "presolar grains" the earliest solid product previously available on earth.

"Each grain probably came from a different star", Dr Heck 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. "The unbelievable thing is we have a rock in our collection that we just take out of the cabinet and learn something about the history of our galaxy".

Latest News