Giant Lasers Simulate Exoplanet Cores, Prove They're More Likely to Have Life
Slashdot reader vikingo9 writes, "By smashing a piece of iron to insanely high pressures, using a laser the size of a football stadium, a team of scientists led by Lawrence Livermore National Laboratory have discovered that exoplanets 4-6 times larger than Earth have an increase chance of harboring biological life." The thinking goes that a molten core "is probably required for life to develop on a planet," Popular Science points out — and this experiment suggests that molten cores of larger rocky exoplanets "should stay hot longer than those within small worlds." "We're finding so many planets, and [one of] the big questions people have are: are these planets potentially habitable?" says Rick Kraus, a physicist at Lawrence Livermore National Laboratory who led the study... Kraus and his team wanted to find other ways to discern whether a planet is habitable. They explored a planet's ability to form a magnetosphere — a magnetic field that protects it from solar radiation, like the one around Earth does for us — as a window into habitability, Kraus says. Life as we know it wouldn't be possible without the Earth's magnetic field. Magnetic fields are a result of molten planetary cores. Earth has a core composed mostly of iron, split into a solid inner core and a liquid outer core. Earth's magnetic field is caused by the convection of the liquid iron, meaning how it swirls: The cooler, denser liquid areas sink to the bottom, while the hotter ones rise like wax in a lava lamp. Studying an exoplanet's core in a laboratory is difficult because there are few ways to recreate such intense pressures and temperatures. This is the first experiment to use iron under pressures that exceed those in Earth's core, Kraus says... The team estimates that it will take a total of 6 billion years for Earth's core to solidify, whereas cores in large exoplanets of similar composition to Earth should take up to 30 percent longer. Of course, the article ends with a few caveats: One issue with extrapolating these results to exoplanets is that those super-Earths can contain elements other than iron in their core, which would change their melting temperature by an unknown amount, Driscoll says. It will also be hard to predict how exoplanets cool because the mantle, the layer of hot rock surrounding the core, plays a huge role in how quickly the core can cool. And those exoplanet mantles could be made of "pretty much anything," he says.
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