Heaviest element yet detected in an exoplanet atmosphere

Utilizing the European Southern Observatory’s Very Massive Telescope (ESO’s VLT), astronomers have found the heaviest component ever present in an exoplanet environment—barium. They have been stunned to find barium at excessive altitudes within the atmospheres of the ultra-hot gasoline giants WASP-76 b and WASP-121 b—two exoplanets, planets which orbit stars exterior our solar system. This surprising discovery raises questions on what these unique atmospheres could also be like.

“The puzzling and counterintuitive half is: why is there such a heavy component within the higher layers of the atmosphere of those planets?” says Tomás Azevedo Silva, a Ph.D. pupil on the College of Porto and the Instituto de Astrofísica e Ciências do Espaço (IA) in Portugal who led the examine printed as we speak in Astronomy & Astrophysics.

WASP-76 b and WASP-121 b are not any peculiar exoplanets. Each are generally known as ultra-hot Jupiters as they’re comparable in dimension to Jupiter while having extraordinarily excessive floor temperatures hovering above 1000°C. This is because of their close proximity to their host stars, which additionally means an orbit round every star takes just one to 2 days. This offers these planets relatively unique options; in WASP-76 b, for instance, astronomers suspect it rains iron.

Besides, the scientists have been stunned to search out barium, which is 2.5 instances heavier than iron, within the higher atmospheres of WASP-76 b and WASP-121 b. “Given the excessive gravity of the planets, we might count on heavy elements like barium to rapidly fall into the decrease layers of the environment,” explains co-author Olivier Demangeon, a researcher additionally from the College of Porto and IA.

“This was in a means an ‘unintended’ discovery,” says Azevedo Silva. “We weren’t anticipating or searching for barium specifically and needed to cross-check that this was truly coming from the planet because it had by no means been seen in any exoplanet earlier than.”

The truth that barium was detected within the atmospheres of each of those ultra-hot Jupiters means that this class of planets is perhaps even stranger than beforehand thought. Though we do often see barium in our personal skies, because the sensible inexperienced coloration in fireworks, the query for scientists is what pure course of may trigger this heavy component to be at such high altitudes in these exoplanets. “In the mean time, we’re not certain what the mechanisms are,” explains Demangeon.

Within the examine of exoplanet atmospheres ultra-hot Jupiters are extraordinarily helpful. As Demangeon explains, “Being gaseous and scorching, their atmospheres are very prolonged and are thus simpler to watch and examine than these of smaller or cooler planets.”

Figuring out the composition of an exoplanet‘s environment requires very specialised gear. The crew used the ESPRESSO instrument on ESO’s VLT in Chile to research starlight that had been filtered by means of the atmospheres of WASP-76 b and WASP-121 b. This made it attainable to obviously detect a number of components in them, together with barium.

These new outcomes present that we have now solely scratched the floor of the mysteries of exoplanets. With future devices such because the high-resolution ArmazoNes excessive Dispersion Echelle Spectrograph (ANDES), which is able to function on ESO’s upcoming Extraordinarily Massive Telescope (ELT), astronomers will have the ability to examine the atmospheres of exoplanets massive and small, together with these of rocky planets much like Earth, in a lot greater depth and to assemble extra clues as to the character of those unusual worlds.

This analysis was offered within the paper “Detection of Barium within the atmospheres of ultra-hot gasoline giants WASP-76b & WASP-121b” which is able to seem in Astronomy & Astrophysics.