A tiny speck of stardust stowed away in the heart of a meteorite found in Antarctica could reveal secrets about the origins of life on Earth.
Stardust From The Early Universe
Discovered by researchers from the University of Arizona, this miniscule grain is believed to have been flung from the explosion of dying star.
Most stellar grains don't survive the cosmic chaos involved in the creation of a solar system or interstellar travel, but in a remarkable feat, this particular one known as LAP-149 made its way to the part of the universe where the solar system now resides. Here, the stellar grain was enveloped in a meteor and eventually fell to Earth.
According to a new paper published in the journal Nature Astronomy, LAP-149 is the only known piece of graphite and silicate grains from a nova, which is a type of stellar explosion.
This single grain of dust gives scientists a peek into an early time in the universe before the sun was even born. Its alien origins could shed light on the formation not just of the planet, but of the entire solar system.
"As actual dust from stars, such presolar grains give us insight into the building blocks from which our solar system formed," explained lead author Pierre Haenecour in a news release from the University of Arizona. "They also provide us with a direct snapshot of the conditions in a star at the time when this grain was formed."
Novae are binary star systems consisting of a dying star known as a white dwarf and a second star. As it slowly dies, the white dwarf steals material from its bigger companion. Eventually, it gets enough stellar material for periodic bursts of energy that create new chemical elements and hurl these elements out into space.
After the Big Bang, there were only a handful of elements. The fresh material from these stellar explosions helped disperse new elements and create the rich, varied cosmos that exist today — including life.
A Window To The Stars
The team of researchers led by Haenecour analyzed the tiny grain down to its atomic level, discovering just how alien it truly was as it was found highly enriched in a carbon isotope known as 13C.
While the carbon isotopic compositions in all samples from anywhere in the solar system varies typically by a factor on the order of 50, Haenecour revealed that the 13C in LAP-149 was found enriched by more than 50,000-fold. According to the team, this is further evidence that carbon- and oxygen-rich grains originating from novae played a role in the building blocks of the solar system.
Analyses also show that LAP-149 is the first known grain to consist of graphite containing an oxygen-rich silicate inclusion.
"We now know that carbonaceous and silicate dust grains can form in the same nova ejecta, and they get transported across chemically distinct clumps of dust within the ejecta, something that was predicted by models of novae but never found in a specimen," said Haenecour.
If scientists could date such stellar grains, they could create a picture of the early galactic neighborhood and trace the origins of the solar system.
This one, LAP-149, contains insufficient atoms for the researchers to determine its age, but the team is hoping that future discoveries will yield similar specimens that are bigger.
