280 light years away

Webb telescope provides weather report for exoplanet

Around 280 light years away from Earth, the exoplanet WASP-43b orbits its star. Despite the enormous distance, astronomers have discovered what wind and temperature conditions prevail in the atmosphere of the gas planet, which is roughly the size of Jupiter.

This was made possible with the help of measurement data from the "James Webb" space telescope as well as climate models and simulations from the Graz Institute for Space Research, as the Austrian Academy of Sciences (ÖAW) reported on Tuesday.

WASP-43b orbits its star in a very close orbit. With the infrared spectrometers of the "Webb" telescope (image below), a complete orbit of WASP-43b, which always turns the same side to its central star when orbiting, could be measured in a specific wavelength range.

Ludmilla Carone from the Institute of Space Research (IWF) at the Austrian Academy of Sciences and her colleague Patricio Cubillos contributed to the interpretation of the measurement data. "Unfortunately, the conditions there are not friendly," as Carone, who is a member of the exoplanet group at the IWF, summarized. The results are published in "Nature Astronomy".

Storms with up to 18,000 kilometers per hour!
The temperatures of its atmosphere are therefore extreme: "On the day side we have temperatures of around 1250 degrees Celsius, on the night side it is a relatively mild 600 degrees, as revealed by observations of the planet's infrared radiation. The storms caused by this enormous temperature gradient can reach speeds of up to 18,000 km/h," Carone explained.

The measurements also revealed that on the night side of the planet, clouds are formed from mineral mixtures, as is known from rocks on Earth. No methane was measured on the night side. This suggests that the vertical mixing caused by updrafts is significantly stronger than originally assumed: if it were calmer, methane would be produced due to the comparatively cooler conditions.

The IWF researchers contributed a three-dimensional climate and wind model to interpret the measurement data. Their predictions were compared with the measurement results and delivered "very good results": "No model is perfect, but we are very satisfied with our results," Carone noted. The conditions on the day side in particular were predicted very well. Patricio Cubillos' atmospheric model in turn made it possible to analyze the methane and water content on both sides of the exoplanet.

"A new era of exoplanet research"
From Carone's point of view, the first steps are being taken "into a new era of exoplanet research": "As soon as we have data from enough exoplanets, we can carry out statistical analyses that tell us how rare or frequent certain climatic conditions are in the universe, for example those on Earth," emphasized Carone.

Further, even more precise measurements on exoplanets should further improve climate models and forecasts in the future - both for the Earth and for other planets, according to the IMF.