Using the ESPRESSO instrument of ESO’s Very Large Telescope, astronomers have found the heaviest … [+]
Scientists using the European Southern Observatory’s (ESO) Very Large Telescope in Chile have for the first time discovered the barium—a silvery-white metal used to make the green color in fireworks—in the upper atmospheres of two exoplanets.
WASP-76 b and WASP-121 b orbit separate stars outside of our solar system. They’re both so-called “hot Jupiters,” gas giant planets like Saturn and Jupiter that orbit very close to their stars. Both planets have surface temperatures above 1,000°C and take just two Earth-days to go around their planet.
A study published in 2020 found it to be likely raining iron on WASP-76 b. Its day-side can reach 2,400º Celsius, high enough to vaporise metals. It’s thought that iron vapor flows to the planet’s cooler night-side where it condenses into iron droplets.
Its discovery—which was made by accident—is confusing to scientists because barium is 2.5 times heavier than iron. It’s the heaviest element found so far in the atmosphere of an exoplanet.
This illustration shows a night-side view of the exoplanet WASP-76 b, where temperatures climb above … [+]
“Given the high gravity of the planets, we would expect heavy elements like barium to quickly fall into the lower layers of the atmosphere,” said Olivier Demangeon, a researcher at the University of Porto and the Instituto de Astrofísica e Ciências do Espaço (IA) in Portugal and co-author of the discovery paper published today in Astronomy & Astrophysics and a researcher from the University of Porto and IA.
“We were not expecting or looking for barium in particular and had to cross-check that this was actually coming from the planet since it had never been seen in any exoplanet before,” said lead author Tomás Azevedo Silva, a PhD student at the University of Porto and the IA.
For now all the discovery does is make “hot Jupiters” an even more mysterious kind of exoplanet than previously. Many hundreds of such planets have been found around distant stars, but without an analog in our own solar system they are poorly understood. However, their size makes their hot, gaseous atmospheres reasonably easy to study, at least compared to smaller, rocky planets that have cooler atmospheres.
Wishing you clear skies and wide eyes.
