Specialists of the European Organization for Astronomical Research in the Southern Hemisphere found that on the exoplanet WASP-76b it rains. This was reported in the journal Nature.
The planet WASP-76b is located in the constellation Pisces at a distance of 640 light-years from Earth. The discovery was made on the basis of the ESPRESSO spectrograph, integrated with the Very Large Telescope in the Chilean Atacama Desert in 2018.
According to the researchers, the red-hot giant WASP-76b receives thousands of times more radiation from the parent star than the Earth from the Sun. The temperature on the sunny side of the exoplanet (it is always turned to the star on one side) rises above 2400 ° C, while on the dark side it is much lower - about 1500 ° C.
On the day side, the sun evaporates particles of iron and other metals from the surface of the planet into its atmosphere. As a result of rotation and under the influence of strong winds, iron vapor is transferred to the cooler night side, condenses and falls to the surface in the form of precipitation.
“It can be said that in the evenings it rains on this planet, though these rains are iron,” said David Ehrenreich, author of the study, professor at the University of Geneva.
The reason for the phenomenon is a large temperature difference between the red-hot day and cooler night sides of the planet, the researchers explain.
ESPRESSO measurements confirmed the presence of iron vapor at the sunset line of planetary day and night, while it was no longer at the border of dawn.
According to him, the only explanation for the disappearance of metallic fumes at the border of dawn is that "on the night side of this extremely harsh exoplanet, it rains iron."
The results obtained by ESPRESSO showed scientists that paired with a very large telescope, this spectrograph has become a powerful tool for studying stellar systems and unusual atmospheres of distant planets.