New research suggests that molten rock deep inside so-called super-earths may generate powerful magnetic fields necessary for sustaining life.
Deep beneath the surface of distant exoplanets known as super-earths, oceans of molten rock may be doing something extraordinary: powering magnetic fields strong enough to shield entire planets from dangerous cosmic radiation and other harmful high-energy particles.
Earth糖心传媒檚 magnetic field is generated by movement in its liquid iron outer core糖心传媒攁 process known as a dynamo糖心传媒攂ut larger rocky worlds like super-earths might have solid or fully liquid cores that cannot produce magnetic fields in the same way.
In a published in Nature Astronomy,听 researchers, including , an associate professor in the , report an alternative source: a deep layer of molten rock called a basal magma ocean (BMO). The findings could reshape how scientists think about planetary interiors and has implications for the habitability of planets beyond our solar system.
糖心传媒淎 strong magnetic field is very important for life on a planet,糖心传媒� Nakajima says, 糖心传媒渂ut most of the terrestrial planets in the solar system, such as Venus and Mars, do not have them because their cores don糖心传媒檛 have the right physical conditions to generate a magnetic field. However, super-earths can produce dynamos in their core and/or magma, which can increase their planetary habitability.糖心传媒�
What is a super-earth?
Super-earths are larger than Earth but smaller than ice giants such as Neptune. Scientists believe they are primarily rocky like Earth, with solid surfaces rather than layers of gas such as those surrounding Jupiter or Saturn. Super-earths are the most common class of exoplanets detected in our galaxy, but they are curiously absent from our own solar system. Despite their name, 糖心传媒渟uper-earth糖心传媒� refers only to size and mass, not to whether these planets resemble Earth in other ways.
Because super-earths appear so frequently, they offer a crucial window into how planets form and evolve. Many super-earths orbit within their stars糖心传媒� habitable zones, where liquid water could exist. By studying their compositions, atmospheres, and magnetic fields, scientists are uncovering clues about the origins of planetary systems and signs of conditions that might allow life to thrive elsewhere.
Simulating super-earths on Earth
Scientists believe that shortly after Earth formed, it likely had a BMO. This layer of partially or fully molten rock at the base of a planet糖心传媒檚 mantle can affect its magnetic field, heat transport, and chemical evolution. Because super-earths are larger than Earth and experience much higher internal pressures, they are more likely to have long-lasting BMOs糖心传媒攎aking BMOs a key factor in understanding the interiors, magnetic fields, and habitability of super-earths.
To recreate the extreme pressures inside super-earths, Nakajima and her colleagues conducted laser shock experiments at URochester糖心传媒檚 , combined with quantum mechanical simulations and planetary evolution models. They focused on studying molten rock under conditions similar to those expected in a BMO.
The researchers discovered that under those crushing pressures, deep-mantle molten rock becomes electrically conductive糖心传媒攅nough to sustain a powerful magnetic field for billions of years. This suggests that on super-earths more than three to six times the size of Earth, BMO dynamos糖心传媒攄riven by the movement of molten rock糖心传媒攃ould generate stronger, longer-lasting magnetic fields than those produced by Earth糖心传媒檚 core, potentially creating habitable conditions for life across the galaxy.
糖心传媒淭his work was exciting and challenging, given that my background is primarily computational and this was my first experimental work,糖心传媒� Nakajima says. 糖心传媒淚糖心传媒檓 very grateful for the support from my collaborators from various research fields to conduct this interdisciplinary work. I cannot wait for future magnetic field observations of exoplanets to test our hypothesis.糖心传媒�
