Meteorite dust holds records of magnetism that may have helped form the sun

Amazing stuff!

"Around 4.6 billion years ago, the solar system was little more than a giant ball of gas and dust. Over the next few million years, this “solar nebula” underwent a huge transformation, flattening into a disk of matter that then condensed to form the central sun and orbiting planets. 

Scientists have assumed that the early solar system was shaped mainly through gravity. But a new study finds that magnetism also likely played a role. 

... scientists have discovered records of ancient magnetism in the oldest samples of meteorites known today. The team analyzed microscopic grains embedded in a meteorite that was discovered in Antarctica in 2008. These grains, called calcium-aluminum-rich inclusions, or CAIs, originally formed during the solar system’s first 200,000 years, making the samples the oldest known solar system material.

The findings suggest that a magnetic field existed very early on, during the time of the solar nebula. The researchers estimate that this nebular magnetic field was stronger than Earth’s magnetic field today, and likely played a significant role in pulling together primordial matter to form the early sun. ..."

From the significance and abstract:

"Significance

A key step in the formation of planetary systems is the collapse of a cloud of gas and dust into a protoplanetary disk. It has been unclear what forces transformed the disk into the final configuration of a central massive star surrounded by planets. In particular, it has been proposed that in the earliest stages of disk evolution gravity and/or magnetism played a central role.

Here we report studies of the remanent magnetization in calcium-aluminum-rich inclusions, the oldest known solar system solids. We find that they record ancient magnetic fields with intensities stronger than that of the Earth today. This supports the hypothesis that magnetism played a key role in driving mass transport in the early protoplanetary disk.

Abstract

The initial stage of planet formation is expected to take place in a nascent protoplanetary disk (PPD) accreting onto the protostar embedded in an infalling envelope.

This stage is likely accompanied by the formation of high-condensation temperature solids resembling calcium-aluminum-rich inclusions (CAIs), the oldest known solar system solids. However, it is unknown whether magnetism and/or gravity dominantly drove accretion in the youngest evolutionary stages of PPDs and the solar nebula.

Here we report paleomagnetic measurements of CAIs indicating that they record a nebular magnetic field of ∼150 to 600 μT.

This intensity is consistent with magnetic fields playing a key role driving disk accretion while also heating the very inner disk to 103 K at the earliest stages of solar system formation."

Meteorite dust holds records of magnetism that may have helped form the sun | MIT News | Massachusetts Institute of Technology "The discovery likely represents the earliest known evidence of a magnetic field in the infant solar system"

Paleomagnetic evidence for a nebular magnetic field from calcium-aluminum-rich inclusions (open access)

Fig. 3 Summary of high-resolution imaging of CAI 11 indicating the presence of primary magnetic phases.