Astronomers have looked into the exoplanet’s atmosphere for the first time and mapped it in three dimensions. They were able to detect hurricane-force winds carrying chemical elements such as iron and titanium.
The discovery was made with the help of ESO’s Very Large Telescope (VLT). The scientists used the ESPRESSO instrument, combining the light from the complex’s four main telescopes into a single signal. This mode allows the detection of much weaker signals that are not available with single observations.
The target of the observations was exoplanet WASP-121, also known as Tylos. It is an ultra-hot Jupiter orbiting a spectral class F star in the constellation Puppis. Tylos’ orbit passes so close to its star that a year on it lasts only about 30 Earth hours. Also, it is always turned the same side to the star, causing it to heat up much more than the reverse side.
Researchers say Tylos’ atmosphere behaves in ways that challenge our understanding of how weather works — not just on Earth, but on all planets. They were able to follow the movement of iron, sodium and hydrogen in their observations. This allowed the winds in the deep, middle and upper atmosphere of the exoplanet to be tracked, and a three-dimensional map of it to be made.
The observations revealed a jet stream that moves matter around the equator and covers about half of the exoplanet. It picks up speed and violently stirs the atmosphere high in the sky as it crosses the hot side of Tylos. Even the strongest hurricanes in the Solar System seem calm in comparison. Scientists have also been able to detect a separate flow in the denser layers of the atmosphere that moves the gas from the hot side to the colder one. Such a climate has not been seen before on any planet.
In addition, the VLT was able to detect the presence of titanium just below the jet stream. This was another surprise, as previous observations of Tylos had shown the absence of this element, possibly because it is hidden deep in the atmosphere.
The discovery clearly demonstrates new possibilities for studying the chemical composition and weather of extraterrestrial worlds. At the same time, even larger telescopes like ESO’s Extremely Large Telescope, whose construction is underway in the Atacama Desert, will be needed to study small Earth-like planets. Scientists hope that the start of its work will be a turning point in the study of exoplanet atmospheres.
According to ESO
