Molten Rock in Super-Earths May Generate Life-Sustaining Magnetic Fields, Study Finds

New research indicates that deep molten rock within super-Earth exoplanets may produce strong magnetic fields essential for supporting life. These magnetic fields could shield planets from cosmic radiation and high-energy particles.On Earth, the magnetic field is generated by movements within its liquid iron outer core. However, larger rocky planets like super-Earths might have solid or entirely liquid cores that are not capable of generating magnetic fields in the same manner.A study published in Nature Astronomy by University of Rochester researchers, including associate professor Miki Nakajima, suggests an alternative source: a deep layer of molten rock known as a basal magma ocean (BMO). These findings offer new perspectives on planetary interiors and the potential for habitability on exoplanets. Nakajima stated that a strong magnetic field is crucial for life on a planet, noting that super-Earths could generate dynamos in their core and/or magma, which would enhance their habitability.Super-Earths are exoplanets larger than Earth but smaller than ice giants like Neptune, and are believed to be primarily rocky. They are the most commonly detected class of exoplanets in our galaxy, with many orbiting within their stars' habitable zones where liquid water could exist.To simulate the extreme internal pressures of super-Earths, Nakajima and her team conducted laser shock experiments at URochester's Laboratory for Laser Energetics, complemented by quantum mechanical simulations and planetary evolution models. Their focus was on studying molten rock under conditions similar to those expected in a BMO.The research revealed that under these intense pressures, deep-mantle molten rock becomes sufficiently electrically conductive to sustain a powerful magnetic field for billions of years. This implies that on super-Earths three to six times Earth's size, BMO dynamos, driven by molten rock movement, could generate magnetic fields stronger and longer-lasting than Earth's core-generated field, potentially fostering habitable conditions across the galaxy.