Now there’s an even greater chance of finding extraterrestrial life!
Researchers have discovered that Earth-like planets in close orbits around dim stars could have magnetic fields strong enough to help protect them from radiation and cosmic rays—meaning these worlds could potentially be more habitable than previously believed.
According to Forbes and the Daily Mail, a team of scientists led by Peter Driscoll, a geophysicist at the Carnegie Institution in Washington DC, found that these exoplanets most likely possess magnetic fields strong enough to protect life on the surface by deflecting charged particles in the stellar winds.
The research, published last week in the journal Astrobiology, used computer models to analyze earth-mass planets that are in close orbit around M-dwarf stars. Driscoll’s team looked at orbital interactions and heat-based simulations, and found these planets are often tidally locked, which means the same side constantly faces the host star due to their gravitational pull.
This gravitational pull also generates tidally-created heat inside the planet, and the more of this tidal heating that a planetary mantle experiences, the better job it does at dissipating its heat and keeping its core cool. This process helps create a magnetic field similar to that found around the Earth, which protects the planet’s atmosphere from being lost to space.
Magnetic fields can form, be sustained for billions of years
The computer simulations, which ranged from one stellar mass (the size of our sun) to about one-tenth of that size, proved false the long-standing notion that tidally-locked planets most likely did not have protective magnetic fields and were thus left exposed to their stars, the authors said.
Co-author Rory Barnes, an astronomer at the University of Washington, explained to Forbes that the simulations generated magnetic fields for Earth-sized exoplanets in most cases—which was a surprise to him, apparently. “I really expected the tidal heating to shut down the magnetic field,” Barnes said, but instead it found that these fields could be sustained for billions of years.
He explained that he believed the tidal heating taking place close to a planet’s surface would suppress the heat flow from the core, which in turn would prevent magnetic field generation. In reality, they found that the simulated world cooled quickly through its surface, which also made it possible for the core to cool down too, and the protective layer to form and persist.
“I was excited to see that tidal heating can actually save a planet in the sense that it allows cooling of the core. That’s the dominant way to form magnetic fields,” Barnes told the Daily Mail. Given that low-mass stars are most active during the first billion years or so of their life spans, he added, “magnetic fields can exist precisely when life needs them the most.”
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Feature Image: NASA
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