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Using computer simulations, an international team of astronomers studied the weather conditions on K2-141b, an Earth-sized exoplanet with supersonic winds raging over 5,000 km / h (3,100 mph), evaporation and precipitation of rocks and an ocean of magma about 100 km (62 miles) deep.
This artist’s impression shows the lava exoplanet CoRoT-7b, which is so close to its Sun-like host star that it has to experience extreme conditions. Image credit: ESO / L. Calcada.
Lava planets are a class of rocky exoplanets that orbit so close to their star that parts of their surface have merged.
Indeed, daytime temperatures on these planets can be high enough to maintain a rock vapor atmosphere.
Theoretical studies on the lava planets and their relatively volatile sodium atmospheres have been published for CoRoT-7b, Kepler-10b, 55 Cnc e, KIC 12556548 and HD 219134b.
“Our 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 future James Webb Space Telescope,” said lead author Giang Nguyen. , PhD student at York University’s Center for Research in Earth and Space Sciences.
Nguyen and colleagues found that about two-thirds of K2-141b are exposed to perpetual daylight, rather than the illuminated hemisphere we are used to on Earth.
Its night side experiences freezing temperatures below minus 200 degrees Celsius (minus 328 degrees Fahrenheit).
The day side, at an estimated temperature of 3,000 degrees Celsius (5,432 degrees Fahrenheit), is hot enough not only to melt the rocks, but also to vaporize them, eventually creating a subtle atmosphere in some areas.
“Our discovery probably means that the atmosphere extends a little beyond the magma ocean shore, making it easier to spot with space telescopes,” said Professor Nicolas Cowan, astronomer in the Department of Earth Sciences and of the Planet at McGill University.
Just like the water cycle on Earth, where water evaporates, rises into the atmosphere, condenses, and falls back as rain, so do sodium, silicon monoxide and silicon dioxide on K2-141b.
On Earth, the rain flows back into the oceans, where it will evaporate once again and the water cycle will repeat itself.
On K2-141b, the mineral vapor formed by the evaporated rock is swept to the freezing side of the night by supersonic winds and the rocks fall back into an ocean of magma.
The resulting currents ebb towards the warm side of the exoplanet, where the rock evaporates once again.
However, the cycle on K2-141b is not as stable as on Earth.
The ocean’s return flow of magma to the diurnal side is slow, and as a result, they predict that the mineral composition will change over time, eventually changing the surface and atmosphere of K2-141b.
‘All the rocky planets, including Earth, started out as molten worlds, but then quickly cooled and solidified,’ said Professor Cowan.
“The lava planets give us a rare glimpse at this stage of planetary evolution.”
A findings paper was published in Royal Astronomical Society Monthly Notices.
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T. Giang Nguyen et al. 2020. Modeling of the atmosphere of the lava planet K2-141b: implications for low and high resolution spectroscopy. MNRAS 499 (4): 4605-4612; doi: 10.1093 / mnras / staa2487
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