The discovery shows that about 4.6 billion years ago, not only gravity, but also magnetism may have helped transform the primordial cloud of gas and dust into the young Sun and its surrounding protoplanetary disk. The results were published in the Proceedings of the National Academy of Sciences (PNAS) by an international team including scientists from the Massachusetts Institute of Technology (MIT) and Purdue University.
The focus of the study is the meteorite DOM 08006, discovered in Antarctica in 2008. The scientists analyzed the calcium-aluminum inclusions, known as CAIs, contained in it. They are among the oldest solid materials in the solar system and formed during the first approximately 200,000 years of its existence.
A magnetic field up to 12 times stronger than Earth's
The minerals have preserved a kind of magnetic “imprint“ of the environment in which they were formed. The analysis shows a magnetic field with an intensity of about 150–600 microteslas, or about 3 to 12 times stronger than Earth's magnetic field today.
This is likely the earliest direct evidence of a magnetic field from the young solar system.
“The transition from a spherical cloud to a protoplanetary disk is one of the most significant events in the entire history of the solar system,“ explains planetary scientist Benjamin Weiss of MIT. The new measurements show that magnetism likely acted in concert with gravity during this transformation.
How magnetism helped the young sun
About 4.6 billion years ago, the solar system was a cloud of gas and dust that gradually collapsed and flattened into a rotating disk. The young Sun formed in its center, and the remaining material later formed planets, asteroids, and other bodies.
The magnetic field may have helped the movement of gas and the transfer of angular momentum in this disk, allowing some of the material to move inward and be absorbed by the young Sun.
DOM 08006 is particularly valuable because it has undergone relatively little change in the billions of years since its formation. Thus, its microscopic minerals have managed to preserve information about conditions at a time when the Earth and the other planets did not yet exist.
The discovery does not question the key role of gravity. It shows that the birth of the solar system was likely the result of a more complex interaction between gravity, gas flows, and strong magnetic fields. This knowledge could also help us understand protoplanetary disks around other young stars, where new planetary systems are being born today.