Recent research published in AGU Advances sheds light on the magnetic influences in the formation of celestial bodies within our solar system, particularly focusing on the asteroid Ryugu. This asteroid, potentially a dormant comet, was visited by Japan's Hayabusa-2 mission, which collected surface and subsurface samples.
The parent body of Ryugu underwent catastrophic collisions and formed much farther from the Sun before migrating inward. Analysis of the collected material revealed evidence of a magnetic field present during its formation, estimated to be around 15 microteslas. This is less than one-third of Earth's current magnetic field and significantly weaker than the magnetic field in the protoplanetary nebula where Earth, Mars, Venus, and Mercury formed, which could have been up to 200 microteslas.
Despite its relative weakness, researchers believe this magnetic field was sufficient to influence the formation of bodies at distances more than seven times that of the Earth to the Sun, including Jupiter, Saturn, Uranus, Neptune, and numerous comets, asteroids, and small worlds.
Co-author Benjamin Weiss, a professor of Earth and Planetary Sciences at MIT, stated, "We show that wherever we look, there was some magnetic field responsible for moving mass to where the Sun and planets formed. Now this applies to the outer planets of the solar system."
The Sun itself formed from a collapsing cloud of interstellar gas, which later became a protoplanetary disk filled with ionized gas interacting with the nascent star through significant magnetic interactions. Gravity, magnetism, and angular momentum of the rotating field subsequently led to planet formation.
The magnetic field dissipated approximately 3-4 million years after the formation of the solar system, raising questions about its role in the early development of planets, as explained by lead author Elias Mansbach.
The research team also examined meteorites believed to have originated from the distant solar system, finding weaker magnetic field readings, yet generally aligning with the upper limit of 15 microteslas.
Weiss noted, "When you are farther from the Sun, a weak magnetic field matters a lot. It was predicted that it should not be so strong there, and that is what we see."
The team looks forward to analyzing the magnetic field of the asteroid Bennu, from which a large sample was collected by NASA's OSIRIS-REx mission. The findings may provide further insights into the original magnetic field where Bennu formed.