A giant exoplanet 855 light-years away is so extreme that it rains liquid and sapphires.
The most detailed analysis to date of the atmosphere of the exoplanet shows for the first time the conditions and dynamics of the permanent night side.
Despite the discovery of thousands of exoplanets, we have only been able to study the atmospheres of a small fraction due to the challenging nature of the observations.
We are moving beyond taking isolated snapshots of specific regions of exoplanet atmospheres to study them as 3D systems.
One of the most famous and well-studied planets we have seen to date is the one in question. It is a gas giant that is almost as big as Jupiter and has a close approach to its star of just 1.27 days. Two years after it was discovered, WASP-121 b became the first exoplanet in which water was found.
It is very unlikely that WASP-121 b could be a good place to live. It is extremely hot, with a temperature range between 1,500 and 3,000Kelvin (1,227 to 2,727 degrees Celsius, or 2,240 to 4,940 degrees Fahrenheit).
The size and proximity of WASP-121 b to its host star, WASP-121, place it firmly in the category of hot Jupiters. Over 300 exoplanets have been confirmed to date, but WASP-121 b is referred to as a prototype for ultra-hot Jupiters.
The WASP-121 b is locked with its star because it is on a very close elliptical path. The exoplanet always has one side facing its star, in permanent hot daylight, while the other side is always facing away. Heavy metals were found in the atmosphere of WASP 121 b's day side.
The day side is 10 times darker than the night side. To obtain more detailed information about the entire exoplanet, the team used the Hubble Space Telescope to observe two full orbits of WASP-121 b, merging data from the day side and night side to see how the atmosphere functions globally.
They were able to observe and reconstruct the full water cycle of an exoplanet for the first time.
We saw the water feature and mapped how it changed at different parts of the planet.
The water cycle on Earth involves phase transitions as water cycles through as a liquid, a Vapor, and a Solid. On the night side, the temperatures are too hot for either the solid or liquid phases of water. On the day side, when the temperature is over 3000 kelvin, the water molecule glows in theIR. The temperature can cause them to break down.
The night side is much cooler than the daytime side. The extreme temperature difference between the hemispheres creates a permanent pressure difference that causes winds to whip around the exoplanet, sweeping the water molecule and atoms with it.
The winds are much faster than our jet stream and can move clouds across the planet in about 20 hours.
When the winds reach the night side of WASP-121 b, the temperatures are cool enough to bring the water back to a Vapor state before it gets carried around to the day side again.
The water would not condense into clouds. The research shows that night side temperatures are low enough that clouds can form from metals previously detected in the atmosphere. There are no aluminum or titanium in these.
The team believes that these elements may have sunk into WASP 181 b's atmosphere, where we can't detect them. The mineral corundum is a form of aluminum oxide. When mixed with other metals, it forms gems.
It could be raining gems on WASP-181 b. Although it could be raining precious gems on Neptune and Uranus, we have no hope of harvesting them, but WASP-181 b shows us what fascinating variety can exist in the different types of worlds out there.
The team is going to take more observations of WASP-181 b with the newly launched James Webb Space Telescope. They want to learn more about how hot Jupiters form. According to our current models of planetary formation, the gravity, radiation, and intense stellar winds should keep the gas from clumping together. The observations might help solve the mystery.
It would be the first time we could measure a carbon-bearing molecule in the atmosphere.
The research was published in Nature Astronomy.
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