Through the stardust, we can trace the history of the galaxy together
50 years ago, a fireball was scratched across the skyline of Victoria, Australia, which split into three pieces and then fell, spreading to 13 square kilometres (or 5 square miles). Today, scientists have found "hidden" interstellar dust particles in meteorites, which date back 5-7 billion years.
Philipp Heck, director of the Field Museum and an associate professor at the University of Chicago as lead author, said: "This is one of the most interesting studies I've ever done, and stardust is the oldest solid material ever found that reveals exactly how stars in galaxies form." ”
Illustration: The large amount of dust produced during the evolution of stars may be the source of pre-solar particles in meteorites
Compared with the stars, human life is like that small gravel, falling into a vast universe of millions of years or even billions of years. Whenever a star dies, the internal particles return to the universe, eventually forming new stars, planets, moons, or meteorites. Stardust is also known as "pre-solar particulate matter". At present, scientists have found stardust in only 5% of meteorites on Earth, and the size of each particle entering the meteorite is about 1/100 of the period marked in the English input method state.
Illustration: Presolar particles (maximum size approx. 8 microns)
In the Field Museum, the largest fragments of the Murchison meteorite are on display, while the remaining fragments are scattered in other museums around the world. Why is stardust named "pre-solar particles"? Formed only because it preceded stars. To separate the presolar particles, the research team crushed the meteorite fragments into powder, then separated them to obtain a final product with a rotten peanut butter odor, and then dissolved them with acid until only stardust remained for analysis.
Illustration: One of the fragments of the Murchison meteorite on display at the Australian Museum
Since it is impossible to directly determine the age of presolar particles, the research team chose "exposure age data" for extrapolation. Heck told Astronomy Online: "Particles interacting with cosmic rays excites new atoms. We count the atoms in the particles (mainly helium atoms and neon atoms), then, the ability to excite the atoms in a known unit time, and the hands of the atoms in the particles, we can find the age of the particles before the sun. This is like placing a bucket outside during a rainstorm, assuming that the rainfall is a fixed value, then according to the amount of water stored in the bucket, it can be calculated how long the bucket is placed in the open rainstorm. ”
Illustration: Cosmic rays produced when a star explodes
The team's findings were published in the Proceedings of the National Academy of Sciences (PNAS). They calculated that most of the particles were between 4.6 and 4.9 billion years old, and some were even older, meaning they were older than the "habitat" of their fall, the Earth (4.5 billion years).
Hecker said: "We also found that there are far more young particles that exist objectively than we expected. And how are the annual slight particles formed? Stars also experienced a "baby boom" 7 billion years ago, and it was the stars that appeared at that time that began to spew dust 4.9 billion years ago, 300 million years before the birth of the solar system. ”
Scientists have long debated whether stars are forming at a constant rate or whether there are fluctuations in volume over time. The particles in the Murchison meteorite apparently complement the theory that stars can suddenly explode, providing strong evidence for the above controversy.
"These particle samples taken from meteorites provide a direct basis for proving that there was indeed a period of star formation enhancement 7 billion years ago—one of the main findings of our study," Hecker said. In addition, they found that the particles would also bond into clumps like cereal, and the scale of the reunion was shocking.
Hecker added: "I was surprised when I found these particles floating in large clumps (over 200 microns) in interstellar space. They may be made of organic viscous substances bonded, and they are similar to cereal blocks made of sugar, but they are also significantly smaller. ”
Illustration: Galaxies
"We look back at the history of the galaxy with excitement. Through the stardust, the oldest material that has arrived on Earth, we can learn about the parent star, the source of carbon in the human body, and the source of oxygen on which we breathe. It is that stardust that takes us back to before the birth of the sun. ”
Resources
1. Wikipedia Encyclopedia
2. Astronomical terms
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