Image: © Berk Ucak | iStock

The MIT discovery suggests that magnetic forces, working alongside gravity, played a crucial role in channelling primordial gas and dust inward to build the infant sun.

Around 4.6 billion years ago, the solar system originated as a giant, spherical interstellar cloud of gas and dust known as the solar nebula. Over a few million years, this cloud underwent a dramatic transformation, flattening into a protoplanetary disk that condensed to form the central sun and surrounding planets.

While astrophysicists have long assumed gravity was the main mechanism driving this collapse, theoretical models have suggested that magnetic fields generated by moving plasma could also provide the necessary torque to transport mass inward.

Previous research led by MIT professor Benjamin Weiss identified magnetic field signatures from roughly 2 million years into the solar system’s history, a period when the Sun was already established, and protoplanets were beginning to form. The new study pushes this timeline back to the very origin of the solar system, testing whether a magnetic field existed when the Sun itself was actively assembling.

Published in the Proceedings of the National Academy of Sciences, the study was led by former MIT graduate student Cauê Borlina (now an assistant professor at Purdue University) alongside Weiss and collaborators from Cambridge, Caltech, UCLA, and Tsinghua University.

To search for the earliest magnetic records, the team analysed DOM 08006, a primitive meteorite discovered in 2008 in the Dominion Range along the East Antarctic Ice Sheet. Unlike the vast majority of meteorites—which underwent heavy thermal or aqueous alteration through planetary collisions and heating—DOM 08006 remained remarkably pristine over its 4.5-billion-year history.

The researchers focused on microscopic components inside the meteorite called calcium-aluminium-rich inclusions (CAIs). These sub-millimetre mineral grains formed during the solar system’s first 200,000 years, making them the oldest known solid materials in existence:

• Isolating magnetic grains:
  • The team carefully surveyed complex CAIs to identify sub-grains containing inherently magnetic, iron-bearing minerals capable of locking in magnetic field orientations during their initial cooling.
• Paleomagnetic testing:
  • Using high-sensitivity paleomagnetic instruments, the researchers measured the remnant magnetisation preserved in these mineral grains.
• Field intensity:
  • The measurements revealed a nebular magnetic field with an estimated intensity of 150 to 600 microteslas, roughly three to 12 times stronger than Earth’s present-day magnetic field.

The presence of such a strong magnetic field during the solar nebula phase demonstrates that electromagnetic forces actively helped move gas and dust from the outer regions of the protoplanetary disk inward toward the central growing star.

By confirming that magnetic fields were active from the earliest moments of solar system history, the researchers demonstrate that magnetism is a fundamental ingredient, alongside gravity, necessary for understanding how stars and protoplanetary systems collapse and evolve across the galaxy