Saturday, 18 January, 2020

Scientists Find 7-Billion-Year-Old Stardust in Murchison Meteorite | Planetary Science

Seven-billion-year-old stardust in meteorite 'oldest solid material found' Oldest solid material on earth is stardust formed 7-billion years ago
Sandy Nunez | 14 January, 2020, 12:57

Stars are formed from massive clouds of dust and gas in space. Some of the grains of this material from a distant region of space came to Earth in the Murchison meteorite that pummeled down in Australia over 50 years ago. The age distribution of the dust - numerous grains were concentrated at particular time intervals - provided clues about the rate of star formation in the Milky Way galaxy, the researchers said, hinting at bursts of stellar births rather than a constant rate.

"They're solid samples of stars, exact stardust", acknowledged lead writer Philipp Heck, a curator at Chicago's Self-discipline Museum and affiliate professor at the College of Chicago.

The discovery of microscopic presolar grains, or stardust, in the Murchison meteorite is a rarity with only five per cent of meteorites found on Earth containing them.

The paper, published in the Proceedings of the National Academy of Sciences, details how Heck and other colleagues examined 40 grains of star dust taken from the Murchison meteorite three decades ago. Fragments of the meteorite totaling 100 kg (220 lb) were found across an area of over 13 sq km (5 sq mi).

"It begins with crushing fragments of the meteorite down correct into a powder", acknowledged co-writer Jennika Greer, from the Self-discipline Museum and the College of Chicago.

Researchers compared the process to burning down a haystack to find the needle. Dissolving the paste in the acid reveals the presolar grains, allowing researchers to determine their age and type of "The researchers were able to measure the exposure of the grains to cosmic rays, highly energetic particles passing through our galaxy". These rays are high-energy particles that travel through our galaxy and penetrate solid matter. Which makes the meteorites and dust solid materials oldest ever found on Earth.

In fact, all the dust motes analyzed in the research come before the formation of the solar system, known as "presolar grains, quot;, with 60 percent of them between 4.6 and 4.9 billion years and the oldest 10 percent It dates back more than 5.6 billion years ago".

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An undated handout picture shows a scanning electron micrograph of a dated presolar silicon carbide grain, which is ~8 micrometers in its longest dimension. Thus, longer the exposure duration would mean more elements are formed. The grain age range has also intrigued scientists: the majority was 4.6 billion to 4.9 billion years, suggesting that an exceptional crop of new stars has formed in the Milky Way il about 7 billion years ago - the lifespan of a star is usually a few billion years.

The researchers also realized that pre-describe voltaic grains in general drift via house stuck collectively in dapper clusters, adore granola. Some grains were believed to be more than 5.5 billion years old - before the Sun was created.

The researchers discovered some of the presolar grains in their sample were the oldest ever discovered based on how many cosmic rays they had soaked up.

Although researchers first identified the grains in 1987 their age could not be determined.

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

Heck notes that there are lifetimes' worth of questions left to answer about presolar grains and the early Solar System. "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", Dr. It beats the oldest rocks on Earth, which were previously considered the most ancient material: zircon crystals discovered in Australia in 2014.