These latest findings demonstrate that we have barely begun to unravel the secrets of exoplanets.
Using the Very Large Telescope (VLT) of the European Southern Observatory, researchers have detected barium, the heaviest element ever discovered in an exoplanet’s atmosphere.
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 nature of the atmospheres in such far-flung places.
Why is there such a heavy element in the higher layers of these planets’ atmospheres is a perplexing and counterintuitive question. The study, which was headed by Tomás Azevedo Silva, a PhD candidate at the University of Porto and the Instituto de Astrofisica e Ciências do Espaço (IA) in Portugal, was reported in Astronomy & Astrophysics today.
Exoplanets WASP-76 b and WASP-121 b are not like other planets. Both are referred to as “ultra-hot Jupiters” because they are almost the same size as Jupiter and with surface temperatures that peak above 1000°C.
This is because they are close to their host stars, so it only takes them one to two days to go around each one. As a result, these planets have some fairly unusual characteristics; on WASP-76 b, for instance, astronomers think it may shower iron.
Even yet, the discovery of barium, which is 2.5 times heavier than iron, in the upper atmospheres of WASP-76 b and WASP-121 b astonished the scientists.
“Given the high gravity of the planets,” as explained by co-author Olivier Demangeon, “we would expect heavy elements like barium to quickly fall into the lower layers of the atmosphere.”
“This was in a way an ‘accidental’ discovery,” adds Azevedo Silva. “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.”
The detection of barium in the atmospheres of both of these extremely hot Jupiters shows that this class of planets may be considerably odd than previously believed.
Although barium is occasionally seen in our own skies as the beautiful green color of pyrotechnics, the puzzle for scientists is what natural process could have caused this heavy element to be at such high altitudes on these exoplanets.
Demangeon says, “at the moment, we are not sure what the mechanisms are”.
Ultra-hot Jupiters are incredibly helpful in the research of exoplanet atmospheres. Demangeon adds, “being gaseous and hot, their atmospheres are very extended and are thus easier to observe and study than those of smaller or cooler planets”.
Very specialized equipment is needed to analyze the atmosphere of an exoplanet.
The researchers 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 made it easy to see that they had different elements, including barium.
These latest findings demonstrate that we have barely begun to unravel the secrets 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: ESO
Image Credit: Getty
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