A team of scientists has studied the actual interstellar dust that served as the building blocks of the solar system some 4.6 billion years ago.
These ancient specks of dust are estimated to be much older than the sun. The researchers were able to collect them from Earth's upper atmosphere where they were deposited after being brought along by comets each time they fly near the sun.
The team studied the actual chemical composition of these ancient interstellar clouds of dust. The team's insights will be significant in the deeper understanding of how the universe was formed.
The scientists, headed by Hope Ishii, a researcher at the University of Hawaii at Manoa, found that the dust contains minute glass-like fragments comprised of metal and sulfides. This chemical composition is scientifically referred to as GEMS.
GEMS are glassy tiny particles that are less than a hundredth of the thickness of a human hair or only tens to hundreds of nanometers in diameter. Some GEMS underwent processes that later on gave birth to the solar system, while some remained as interstellar dust. The remainder of the ancient dust was able to survive the space because they were attached to comets, which are known to be cold astronomical bodies formed in the exterior of the solar nebula.
By studying GEMS' nanoscale chemical composition using electron microscopes, the scientists concluded that the building blocks of the solar system are made up of carbon, ices, and disordered silicate.
"Our observations suggest that these exotic grains represent surviving pre-solar interstellar dust that formed the very building blocks of planets and stars," Ishii highlighted.
The experiments were held at the Department of Energy's Lawrence Berkeley National Laboratory.
Grains And Subgrains Of Ancient Interstellar Dust
For their study, published on June 11 in the journal Proceedings of the National Academy of Sciences, the team mapped GEMS' detailed element distributions and found that the tiny glassy particles are actually made up of even tinier subgrains. These minute subgrains had started to stick together even before the comets were formed.
GEMS' subgrains stuck together in a cluster through a dense organic carbon. Essentially, a grain of GEMS is made up of clusters of these subgrains. When comets pass by GEMS, the grains stick to the comets through a less dense organic carbon composition and later on become the interstellar dust.
The Ancient Building Blocks
The carbon that glues the grains and subgrains together disintegrate by the slightest temperature, the experiment revealed. Through this, the team concluded that these dust came from a very cold environment that could be outside the solar nebula or even outside the pre-solar molecular cloud.
"Therefore, these interplanetary dust particles survived from the time before formation of the planetary bodies in the solar system," highlighted Jim Ciston, a staff scientist at the Molecular Foundry at the Lawrence Berkeley National Laboratory.