Astronomers using the NASA/ESA Hubble Space Telescope have detected massive cyclones and other dynamic weather activity swirling on WASP-121b, an ultrahot-Jupiter exoplanet approximately 881 light-years away in the constellation of Puppis.
WASP-121b is a gas-giant exoplanet 1.87 times bigger than Jupiter and 1.18 times more massive.
First discovered in 2016, this alien world takes just 1.3 days to orbit its parent F6-type star, WASP-121.
WASP-121b is so close to the star that if it got any closer, the star’s gravity would start ripping it apart.
Astronomers estimate the planet’s temperature to be about 2,500 degrees Celsius (4,600 degrees Fahrenheit), hot enough to boil some metals.
In the new research, Caltech astronomer Jack Skinner and his colleagues analyzed observations of WASP-12 b taken by Hubble in 2016, 2018, and 2019.
The researchers found that the planet has a dynamic atmosphere, changing over time.
They used sophisticated modeling techniques to demonstrate that these dramatic temporal variations could be explained by weather patterns in the exoplanet’s atmosphere.
They found that WASP-121b’s atmosphere shows notable differences between observations.
Most dramatically, there could be massive weather fronts, storms, and massive cyclones that are repeatedly created and destroyed due to the large temperature difference between the star-facing side and dark side of the exoplanet.
The authors also detected an apparent offset between the exoplanet’s hottest region and the point on the planet closest to the star, as well as variability in the chemical composition of the exoplanet’s atmosphere (as measured via spectroscopy).
They reached these conclusions by using computational models to help explain observed changes in the exoplanet’s atmosphere.
“The remarkable details of our exoplanet atmosphere simulations allow us to accurately model the weather on ultrahot planets like WASP-121b,” Dr. Skinner said.
“Here we make a significant step forward by combining observational constraints with atmosphere simulations to understand the time-varying weather on these planets.”
“This is a hugely exciting result as we move forward for observing weather patterns on exoplanets,” said Dr. Quentin Changeat, an astronomer at the Space Telescope Science Institute.
“Studying exoplanets’ weather is vital to understanding the complexity of exoplanet atmospheres on other worlds, especially in the search for exoplanets with habitable conditions.”
“The assembled data-set represents a significant amount of observing time for a single planet and is currently the only consistent set of such repeated observations.”
“The information that we extracted from those observations was used to infer the chemistry, temperature, and clouds of the atmosphere of WASP-121b at different times.”
“This provided us with an exquisite picture of the planet changing over time.”
Quentin Changeat et al. 2024. Is the atmosphere of the ultra-hot Jupiter WASP-121b variable? ApJS, in press; arXiv: 2401.01465