[ad_1]
Posted on Apr 29, 2019
Tucked inside a chondritic meteorite collected in Antarctica, the tiny speck represents actual stardust, most likely exploding in space by an exploding star before our own sun existed. Although such grains are believed to be important in the formation of plants, they rarely survive the earth that goes with the birth of a solar system.
Billions of years ago, before our solar system was born, a dead star known to a white dwarf in a nearby binary star system accumulated enough material from its companion to cause it to 'go nova.' The stellar explosion forged dust grains with exotic compositions not found in our solar system.
A team of researchers led by the UA found such a grain (inset image above), encased in a meteorite, that survived the training of our solar system and analyzed it with instruments sensitive to the single atoms in a sample. Measuring one of 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 to be in the same nova eruption.
A grain of dust forged in the death throes of a long-gone star was discovered by a team of researchers led by the University of Arizona.
The discovery challenges some of the current theories about how the planet is growing up with the raw materials for the formation of planets and, ultimately, the precursor molecules of life.
"Antarctica Alert" -Ghostly Supermassive Black Hole Invader Detected
"As actual dust from stars, such presolar grains give us insight into the building blocks from which our solar system," said Pierre Haenecour, lead author of the paper, which is scheduled for advance online publication on Nature Astronomy's website on Apr. 29. "They also provide a direct snapshot of the conditions when the grain was formed."
Dubbed LAP-149, the dust grain represents the only known assembly of graphite and silicate grains that can be traced to a specific type of stellar explosion called a nova. Remarkably, it survived the journey through space and traveled to the region some 4.5 billion years ago, perhaps earlier, where it became embedded in a primitive meteorite.
Unknown Beams Detected Shooting Up from Depths of Antarctica's South Pole – "May Shatter the Standard Model of Physics"
Novae are binary star systems in which a core of a star, called a white dwarf, is on its way to fading out of the universe, while its companion is either a low-mass main sequence star or a red giant. The white dwarf then begins with syphoning material off its bloated companion. Once again it is enough to write a new material, the white dwarf re-ignites in periodic outbursts violent forge to new chemical elements of the stellar fuel and spew them deep into space, where they .
From the Farside -NASA Massive Gravity Anomaly Buried Under Antarctica
Since shortly after the Big Bang, when the universe of hydrogen only, helium and traces of lithium, stellar explosions have contributed to the chemical enrichment of the cosmos, resulting in the plethora of elements we see today.
Taking advantage of sophisticated ion and electron microscopy at the University of Lunar and Planetary Laboratory, a research team led by Haenecour analyzed the microbe-sized dust grain down to the atomic level. Alien-highly enriched in a carbon isotope called 13C.
"The carbon isotopic compositions in anything we have ever heard of, or planet in our solar system," said Haenecour, who will join the Lunar and Planetary Laboratory as an assistant professor the fall. "The 13C we found in LAP-149 is more than 50,000-fold. These results provide further laboratory evidence that both carbon-and-oxygen-rich grains from contributed to the building blocks of our solar system.
Although their parent, the isotopic and chemical compositions and microstructure of individual stardust grains identified in meteorites provide unique constraints and training in thermodynamic conditions in stellar outflows, the authors wrote.
LAP-149 is the first known grain of graphite that contains an oxygen-rich silicate inclusion.
"We have a glimpse into a process we could never witness on Earth," Haenecour added. "It tells us how to dust grains form and move around inside as they are expelled by the nova. We now know that carbonaceous and silicate dust grains can be formulated into the same nova ejecta, and they get transported across chemically distinct clumps of dust within the ejecta, something that has been predicted by models of nanoparticles but never found in a specimen.
Unfortunately, LAP-149 does not contain enough atoms to determine its exact size, so it is possible to find specimens in the future.
"If we could date these objects someday," said Tom Zega, scientific director of the Kuiper Materials Imaging and Characterization Facility and associate professor in the Lunar and Planetary Laboratory and Department of Materials Science and Engineering. "Perhaps we are living in a supernova explosion, compressing clouds of gas and dust with its shockwave, igniting stars and creating stellar nurseries, similar to what we see in Hubble's famous 'Pillars of Creation' picture."
The meteorite containing the speck of stardust is one of the most pristine meteorites in the Lunar and Planetary Laboratory's collection. Classified as a carbonaceous chondrite, it is believed to be analogous to the material on Bennu, the target asteroid of the UA-led OSIRIS-REx mission. By taking a sample of Bennu and bringing it back to Earth, the OSIRIS-REx mission team hopes to provide scientists with what has been little, if any, alteration since the formation of our solar system.
Until then, researchers depend on LAP-149, which is more likely to be exploding, than it would have been in the future.
"It's remarkable when you think about it all along the way that should have killed this grain," Zega said.
The Daily Galaxy via University of Arizona
Image credit: University of Arizona
[ad_2]
Source link