Barium, the heaviest element ever found in the atmosphere of an exoplanet, has been found by astronomers. They were shocked to find barium in the atmospheres of the exoplanets WASP-76 b and WASP-121 b, two extremely hot gas giants that orbit stars outside of our solar system. This unexpected finding prompts speculation about the potential characteristics of these strange environments.
Why is there such a heavy element in the upper layers of these planets’ atmospheres is a perplexing and counterintuitive question. Tomas Azevedo Silva, a PhD candidate at the University of Porto and the Portuguese Institute of Astrophysics and Space Sciences (IA), led the study that was just released in Astronomy & Astrophysics.
Exoplanets WASP-76 b and WASP-121 b are not like other planets. Both are referred to as “ultra-hot Jupiters” because they are roughly the same size as Jupiter and have surface temperatures that soar above 1000°C. As a result of their close proximity to their host stars, an orbit takes only one to two days for each star. As a result, these planets have some rather unusual characteristics; on WASP-76 b, for instance, astronomers think it may rain iron.
Even so, the discovery of barium, which is 2.5 times heavier than iron, in the upper atmospheres of WASP-76 b and WASP-121 b surprised the scientists.
According to co-author Olivier Demangeon, a researcher from the University of Porto and IA, “given the high gravity of the planets, we would expect heavy elements like barium to quickly fall into the lower layers of the atmosphere.”
According to Azevedo Silva, this discovery was somewhat accidental. Barium was not something we were expecting or specifically looking for, so we had to double-check that it was coming from the planet because it had never been observed in an exoplanet before.
Both of these ultra-hot Jupiters had barium found in their atmospheres, which suggests that this class of planets may be even stranger than previously believed.
The question for scientists is what natural process could cause this heavy element to be at such high altitudes in these exoplanets, despite the fact that we do occasionally see barium in our own skies as the brilliant green colour in fireworks. Demangeon says, “At the moment, we are unsure of the mechanisms.
Ultra-hot Jupiters are incredibly helpful in the study of exoplanet atmospheres. They have very extended atmospheres due to being gaseous and hot, which makes them easier to observe and study than those of smaller or cooler planets.
Very specialised equipment is needed to analyse the atmosphere of an exoplanet.
The team examined starlight that had been filtered through the atmospheres of WASP-76 b and WASP-121 b using the ESPRESSO instrument on ESO’s VLT in Chile. This allowed for the easy identification of a number of elements in them, including barium.
These new findings demonstrate that we have only begun to unravel the mysteries of exoplanets. Future telescopes like the Extremely Large Telescope (ELT) of the European Southern Observatory (ESO) will be equipped with instruments like the high-resolution ArmazoNes high Dispersion Echelle Spectrograph (ANDES), which will allow astronomers to study the atmospheres of exoplanets large and small, including those of rocky planets similar to Earth, in much more detail and to glean more information about the nature of these strange worlds.
(source : ANI)
