The heaviest element ever found in an exoplanet atmosphere is barium. They were surprised to find barium in the atmospheres of the WASP-76 b and WASP- 121 b gas giants. There are questions about what these atmospheres may be like.
Toms Azevedo Silva is a PhD student at the University of Porto and the Instituto de Astrofsica e Ci.
The WASP-76 b and WASP- 121 b are not ordinary planets. Both are known as ultra-hot Jupiters as they are similar in size to Jupiter and have very high surface temperatures. Astronomers think it rains iron on WASP-76 b.
The scientists were surprised to find that barium is 2.5 times heavier than iron in the upper atmospheres of WASP-76 b and WASP- 121 b. "We would expect heavy elements like barium to quickly fall into the lower layers of the atmosphere because of the high gravity of the planets," says co-author Olivier Demangeon.
Azevedo Silva says it was an accident. Since it had never been seen in any exoplanet before, we had to cross-check that this was actually coming from the planet.
The fact that barium was found in the atmospheres of both of these Jupiters suggests that this category of planets may be even stranger than previously thought. Although we occasionally see barium in our own skies, as the brilliant green color in fireworks, the question for scientists is what natural process could cause this heavy element to be at such high altitudes Demangeon says they don't know what the mechanisms are.
Ultra-hot Jupiters are used in the study of atmospheres. Demangeon says that being gaseous and hot makes it easier to observe and study.
It takes very specialized equipment to determine the composition of an exoplanet. The team used the instrument on the VLT to analyze the starlight that had passed through the atmospheres of WASP-76 b and WASP- 121 b. It was possible to see several elements in them.
The new results show that the mysteries of exoplanets have not been fully explored. Astronomers will be able to study the atmospheres of exoplanets large and small with future instruments such as the high-resolution ArmazoNes high Dispersion Echelle Spectrograph.
The paper "Detection of Barium in the atmospheres of ultra-hot gas giants WASP-76b and WASP-121b" will be published in Astronomy and Astrophysics.
More information: T. Azevedo Silva et al, Detection of barium in the atmospheres of the ultra-hot gas giants WASP-76b and WASP-121b, Astronomy & Astrophysics (2022). DOI: 10.1051/0004-6361/202244489 Journal information: Astronomy & Astrophysics
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