WASP-43B: An exoplanet with clouds of liquid rock
The exoplanet WASP-43b is a world like no other — and full of extremes. There is nothing remotely comparable in our solar system.
© T. Müller / MPIA / HdA (excerpts)
An artist's rendering of hot Jupiter WASP-43b orbiting its host star in a close orbit.
The exoplanet WASP-43b is an inhospitable world, which may not exist on a cosmic scale any time soon — and whose characteristics will still be cautiously described as “extreme.” This hot Jupiter orbits its star WASP-43 in just 19.5 hours and at a very close distance, resulting in large temperature differences across the celestial body. This is proven by the global temperature distribution map from WASP-43b, It was created by a team led by Laura Kreidberg from the Max Planck Institute for Astronomy in Heidelberg.
To do this, the working group evaluated infrared data recorded by the James Webb Space Telescope. While the average temperature on Jupiter in our solar system is minus 135 degrees Celsius, on WASP-43b it fluctuates between 600 degrees Celsius on the night side and 1,250 degrees Celsius on the day side facing the Sun: since the planet is close to the Sun . Distance from its planet star races, alignment of day and year; It takes the same time to revolve around a star as it takes for a planet to rotate around its axis. Thus, the star always illuminates and heats the same side of the planet. This is called “restricted alternation.”
The extreme temperature variations ensure the emergence of violent winds as a compensatory movement, reaching speeds of up to 9,000 kilometers per hour. However, temperature variation cannot be explained solely by differences between day and night. Model calculations carried out by the working group then confirmed data from various space telescopes that there were clouds on the dark side, reducing the planet's infrared radiation here.
It is not clear what type of clouds these are: given the high temperatures, they are neither water vapor nor ammonia clouds, as they will not condense in the heat. Instead, Kreidberg and his colleagues suspect that the clouds could be composed of evaporated rocks and metals: dayside heating would be enough for that.
Water vapor is distributed throughout the planet, while methane is absent – which is surprising since this gas is already common on hot Jupiter. The necessary reactants would likely pass through the cooler night side so quickly that there would be little time for the expected chemical reactions to produce enough detectable methane. Each piece of methane, no matter how small, is thoroughly mixed with other gases, which are quickly pushed to the dayside, where the methane will be destroyed by the heat.
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Physical Astronomy 10.1038/s41550–024–02230-x, 2024
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