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Scientists have found an exoplanet of molten lava oceans where they forecast supersonic winds and “rocky rain.”
A fiery hot world that orbits its star so closely that a year takes less than seven hours, K2-141b is among the most extreme planets discovered thus far beyond the Solar System.
According to a study published in Monthly Notices of the Royal Astronomical Society, scientists from McGill University, York University and the Indian Institute of Science Education, K2-141b has a surface, ocean and atmosphere all made up of the same thing—rock.
It’s thought that K2-141b is a place where rock is vaporized and falls as a mineral “rocky rain” that replenishes an ocean of molten lava.
What is K2-141b?
According to NASA’s exoplanet catalog, K2-141b is a “super-Earth” whose mass is about five times that of our planet. That mass suggest that it’s a terrestrial rocky planet like Earth.
However, it’s got “extreme geometry.”
It orbits its star, a K-type or “orange dwarf” star that’s cooler than our Sun and much younger, every 0.3 Earth-days. That super-quick orbit is explained by its closeness to its host star. K2-141b is just 0.7% of the distance between Earth and our Sun. For comparison, Mercury is about 40% of that distance.
Where is K2-141b?
K2-141b is one of two planets in a star system 202 light-years from our Solar System within the constellation of Aquarius, the water bearer. The star is too dim to be seen from Earth.
It was found in data from the Kepler Space Telescope’s “K2 mission,” which spotted two planets transiting across the host star.
It’s also been found by the HARPS-N spectrograph, an instrument on the 3.5 meter Italian Telescopio Nazionale Galileo at the Roque de los Muchachos Observatory La Palma in the Canary Islands, Spain.
What is so strange about K2-141b?
It features a magma ocean 62 miles/100 km deep and is way too hot to be habitable. So hot, in fact, that rock vaporizes.
Using spectroscopy—data on the planet’s illumination—the researchers found that two-thirds of K2-141b faces perpetual daylight. While its below -200 C on the night-side, the day-side sees 3,000 C temperatures, which is hot enough to vaporize rock and create a thin atmosphere in some areas.
“Our finding likely means that the atmosphere extends a little beyond the shore of the magma ocean, making it easier to spot with space telescopes,” said Professor Nicolas Cowan, a professor in the Department of Earth & Planetary Sciences at McGill University.
What’s the weather like on K2-141b?
The scientists used computer simulations to predict the conditions on K2-141b and found supersonic winds that rage over 3,100 mph/5,000 kmph.
However, it’s those high temperatures on its day-side that create something bizarre; a cycle something like Earth’s water cycle, but with rock. It’s so hot that rock is thought to evaporate and precipitate.
In short, it rains rock.
Just as water evaporates, rises into the atmosphere, condenses, and falls back as rain here on Earth, on K2-141b the same cycle may occur with sodium, silicon monoxide and silicon dioxide on K2-141b. This mineral vapor formed by evaporated rock appears to be swept to the planet’s night side by those supersonic winds where rocks fall as rain into the magma ocean.
It’s thought to be a much slower cycle that the water cycle on Earth, but K2-141b’s extreme weather could, say the scientists, permanently change the surface and atmosphere of K2-141b over time.
“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,” said lead author Giang Nguyen, a PhD student at York University who worked under the supervision of McGill University Professor Cowan on the study.
NASA’s James Webb Space Telescope will launch on October 31, 2021, and is expected to change cosmology as we know it by allowing much better quality observations of distant exoplanets.
What else do we know about K2-141b?
As well as having one of the shortest known orbital periods of any confirmed exoplanet, K2-141b is a particularly dense exoplanet, which could mean its has a huge iron core.
Does K2-141b have any sister planets?
So far only one other planet in the K2-141 star system has been found—K2-141c. A “hot Neptune” gas giant planet, its mass is 7.4 Earths and it takes 7.7 days to complete one orbit of its star.
“All rocky planets, including Earth, started off as molten worlds, but then rapidly cooled and solidified,” said Cowan. “Lava planets give us a rare glimpse at this stage of planetary evolution.”
Wishing you wide eyes and clear skies.