Meteorites can tell us very interesting stories about our origins in the universe. This is what one found in Antarctica has done and inside which a team of researchers led by the University of Arizona (USA) has discovered a hidden grain of dust that was forged during an explosion of a star that disappeared thousands of years ago. millions of years and preceded our Sun. Knowledge of the physical properties of these particles is very important to astronomers.
This recent discovery, published in Nature Astronomy , challenges, according to the University of Arizona (UA) in a press release, some of the theories that currently exist about how dying stars provide the universe with raw materials for the formation of planets. and, ultimately, life-precursor molecules.
Shortly after the Big Bang occurred, when the universe was composed exclusively of hydrogen, helium, and lithium, stellar explosions contributed to the chemical enrichment of the cosmos , and that led to the large number of elements that we have today.
It is quite likely that the speck this study talks about was thrown into space during the explosion of a star that disappeared before the Sun emerged. Unfortunately, such particles are not easy to find, as they rarely survive the turbulent scenario that accompanies the birth of stars and planets.
A born survivor
It is surprising that this grain of dust, christened LAP-149, could survive the journey through interstellar space and travel to the region that became our Solar System some 4.5 billion years ago, perhaps earlier, where it was embedded in a primitive meteorite.
“These presolar grains (solid matter in the form of tiny solid grains originated at a time before the formation of the Sun) give us an idea of the building blocks from which our Solar System was formed “, explains Pierre Haenecour, author main article. “They also provide us with a direct photo of the conditions that exist in a star at the time this particle was formed,” he adds.
The team led by Pierre Haenecour analyzed the microbe-sized dust grain down to the atomic level, and it turned out to be very strange, highly enriched in an isotope of carbon called 13C. “The results obtained provide additional laboratory evidence that both the carbon- and oxygen-rich grains of the novae contributed to the building blocks of our Solar System ,” explains Haenecour.
A detailed analysis also revealed more unexpected surprises: Unlike similar dust grains believed to have been forged in dying stars, LAP-149 is the first to consist of graphite containing an inclusion of oxygen-rich silicate. Unfortunately, it does not contain enough atoms to determine what its exact age might be, although researchers are confident that they will be able to find similar, but larger, particles in the future.
“If we could date them someday, we could get a better idea of what our galaxy was like in our region and what triggered the formation of the Solar System ,” says Tom Zega, scientific director and professor at the UA. “Perhaps we owe our existence to the explosion of a nearby supernova,” he adds.
The material of the meteorite, analogous to that of the asteroid Bennu?
The meteorite that contains this speck of stardust is one of the most unaltered in the collection of the UA Lunar and Planetary Laboratory. Classified as carbonaceous chondrite, its material is believed to be analogous to that of Bennu , a near-Earth asteroid discovered in 1999 and about 490 meters in diameter.
This asteroid is the objective of the mission of the space probe OSIRIS-REx, which is on its surface to collect samples of dust and rock fragments – about 60 grams in total – with a robotic arm and bring them back to Earth – expected in September 2023–.
Image: University of Arizona / Heather Roper
