Extreme exoplanet likely has lava oceans and rain made of rocks
With well over 4,000 exoplanets discovered to date, there are worlds out there so weird they’d put Dr. Who writers to shame. The latest to join the ranks is K2-141b, a scorching planet where it rains rocks, winds whip around at supersonic speeds and huge swaths of the surface are covered in lava oceans.
Discovered in 2018 by Kepler’s Second Light mission, K2-141b is a rocky Super-Earth that’s about 50 percent bigger than our home planet, but five times denser. It has one of the shortest “years” of any known planet, zipping around its host star once every 6.7 hours. Of course, you can’t get that close to a star and not feel the burn, so temperatures are expected to soar.
In the new study, researchers from McGill and York Universities and the Indian Institute of Science Education simulated the atmosphere and weather of K2-141b, by studying the spectrum of light from the star filtering through the planet’s atmosphere.
And the picture they paint is one of the most extreme exoplanets ever described. The simulations suggest that K2-141b has a system similar to Earth’s water cycle – fluid oceans, and atmospheric vapor that condenses and falls as rain. The difference is that on this exoplanet the cycle isn’t water, but rocks.
K2-141b is tidally locked to its star, meaning about two thirds of the planet is constantly bathed in daylight. That heats up the day side to a sweltering 3,000 °C (5,432 °F), melting the surface into a vast lava ocean, 100 km (62 mi) deep. But it doesn’t stop there – that heat is enough to actually vaporize rocks, creating an atmosphere of largely silicon dioxide.
Meanwhile, the night side of the planet never sees any light, so temperatures there plunge below -200 °C (-328 °F). That huge temperature differential creates incredibly strong winds clocking speeds over 5,000 km/h (3,100 mph). These supersonic winds carry the vaporized rocks around to the night side of the planet, where it cools, condenses and falls as a rocky rain.
But it’s not a completely stable system, the team says. It takes a while for the magma ocean to flow from the night side to the day side, so the overall mineral composition of the surface and atmosphere of the planet will probably change over time.
Of course, all of this remains simulated speculation for now, but the researchers say that their predictions could be checked in the near future.
“The study is the first to make predictions about weather conditions on K2-141b that can be detected from hundreds of light years away with next-generation telescopes such as the James Webb Space Telescope,” says Giang Nguyen, lead author of the study.
The research was published in the journal Monthly Notices of the Royal Astronomical Society.
Source: McGill University