The basic material by which planets and the solar system are made of is stardust. But the origin of stardust remained a puzzle for scientists. Now an international team of scientists has solved it.
The grains had been a challenge with regard to its origin as they date beyond the solar system's birth.
The grains of stardust are still recovered from meteorites that fall to Earth.
Researchers who studied the topic also had scientists from the University of Edinburgh hold experiments at an underground facility in Italy.
The Laboratory for Underground Nuclear Astrophysics or LUNA was led by the Italian Institute for Nuclear Physics Gran Sasso Laboratory.
"It is a great satisfaction to know that we have helped to solve a long-standing puzzle on the origin of these key stardust grains," said Marialuisa Aliotta, an astronomer at the University of Edinburgh.
She said the study proved the importance of precise measurements required in nuclear reactions taking place within stars.
The study is published in Nature Astronomy.
Origin From AGB Stars
The study traced the origin of stardust to Asymptotic Giant Branch or AGB stars. From this basic source, the solar system took birth from a cloud, 4.6 billion years ago, according to the study.
AGB stars have six times the size of the sun and are extremely bright. They shake off external layers when the inner cores bulge out.
The departed layers of the red star convert themselves into gas and dust clouds and start begetting new stars and protoplanetary disks.
Though the bulk of the stardust grains is lost in the planet-making process, a tiny fraction has survived, which is seen in meteorites that periodically hit Earth's surface.
Intricate Nuclear Process
The study has underlined that the frequency of the reaction during AGB fusion is the ultimate key that decides the grain's composition as the vestiges carried by meteorites.
The dust grain's composition is a miniature theater of the nuclear processes that take place in the stars from where they originated.
So far researchers were attributing the grain's properties to AGB stars considering AGB's ability to produce huge amounts of dust. But the dilemma was that grains taken from many of the meteorites were not matching the properties expected from such AGB stars, researchers noted.
Puzzle Solved
That dichotomy was resolved by studying the make-up of meteoritic dust grains in respect to nuclear reactions occurring in AGB stars.
A fusion reaction triggers between 17O — a heavier version of oxygen and protons — which the team watched during the underground lab experiments.
Scientists noticed that those nuclear reactions were holding valid in stardust grains that were contained in meteorites as well. That was the end of the mystery, the team said.
The LUNA Collaboration also had scientists representing institutions from Germany, Italy, Hungary and the UK.
