Astronomers have made a groundbreaking discovery, observing magnetic fields shaping new planets for the first time. This study, led by Richard Teague of MIT, reveals a magnetic field about 10 milligauss in strength, gently guiding material around the young star TW Hydrae. The observations were made using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, a network of high-precision radio antennas that captures faint signals from space.
The team detected a field roughly a thousand times weaker than a fridge magnet, yet strong enough to organize matter across a star-system-sized region. By mapping the field across a broad ring in the disk, they found that it changes orientation where the dust and gas show strong structure. This is the best look we’ve ever had at the invisible hand shaping the birthplaces of new worlds.
The study offers the clearest evidence yet that magnetic fields actively sculpt the environments where planets take shape. Magnetic fields can haul gas inward, shed angular momentum outward, and launch outflows that help disks thin and clear. They also influence where dust piles up enough to form planet cores and set the clock for when gas giants can grow before the disk disperses.
The detection spans tens of billions of miles across the disk and reaches into regions where icy bodies may form. It reveals how weak fields can still orchestrate large-scale flows and ties to the chemistry we see in planet-forming zones. The method used works at low radio frequencies where ALMA excels in sensitivity and stability, allowing for longer tracks and more detailed comparisons.
The study is published in The Astrophysical Journal Letters and marks a turning point, linking magnetic structure directly to how planets take shape. It transforms magnetism from a long-suspected influence into a clearly measured force in planet formation. With ALMA's upcoming wideband sensitivity upgrade, astronomers will be able to make even more detailed measurements and build magnetic maps for disks at different ages and masses.
