Astronomers have discovered two unexpected chemical elements in the atmospheres of two scorching exoplanets that are falling from the sky with liquid iron and gems.
Two exoplanets that orbit different stars outside of our solar system are superhot gas giants called WASP-76b and WASP-121b. Astronomers have used the European Southern Observatory’s Very Large Telescope to detect high-altitude barium in every exoplanet’s atmosphere.
Barium is the heaviest element ever found in an exoplanet’s atmosphere. Science Magazine Astronomy and astrophysics published a study Thursday detailing the discovery.
With each revolution, WASP-76b and WASP-121b look more and more strange to scientists.
“The intriguing and controversial part is why do these planets have such a heavy element in their upper atmospheres?” said study author Thomas Azevedo Silva, a PhD student at the University’s Institute of Astrophysics and Space Sciences. .
“In a sense, it was an “accidental” discovery. We didn’t expect or look for barium in particular, and had to make sure it really came from the planet, as it’s never been seen on any exoplanet.”
The two exoplanets are similar in size to Jupiter, the largest planet in our solar system, but have incredibly hot surfaces that exceed 1,000 degrees Celsius.
The high temperatures of WASP-76b and WASP-121b are due to each planet being close to its parent star, orbiting in a day or two.
Originally discovered in 2015, WASP-121b is about 855 light-years from Earth. The exoplanet has a glowing atmosphere of water vapor, and the strong gravitational pull of the star it orbits warps it into the shape of a rugby ball.
The planet is tidally locked, which means it is always on the same side facing the star. This is similar to how our Moon revolves around the Earth. On the dayside, temperatures start at 2227°C in the deepest layer of the atmosphere and reach 3227°C in the upper layer.
Scientists first discovered WASP-76b in 2016. It orbits a star in the constellation Pisces, 640 light years from Earth. This exoplanet is also held back by the tide, so on the dayside the temperature exceeds 2426 ºC.
The scorching nature of exoplanets has endowed them with unusual features and climates that feel straight out of science fiction. Scientists believe that liquid iron rains down from the sky on WASP-76b, while metal clouds and liquid gems form on WASP-121b.
The illustration shows an image of the night face of exoplanet WASP-76b, with liquid iron raining from the sky. M. Kornmesser/European Southern Observatory
The discovery of barium in the upper atmospheres of two planets surprised researchers. The element is 2.5 times heavier than iron.
“Given the high gravity of the planets, one would expect heavy parent elements such as barium to fall rapidly into the lower atmosphere,” said study co-author Olivier Demangeon, a research fellow at the Institute of Astrophysics and Sciences. Space of the University of Porto.
The detection of barium in the atmospheres of two exoplanets may suggest that superhot gas giants have even more unusual properties than we thought.
On Earth, barium appears in the night sky as a bright green color when fireworks explode. But scientists aren’t sure what the natural process is that causes this heavy element to appear so high in the atmosphere of these gas giants.
The research team used the ESPRESSO instrument or the Echelle spectrograph for rocky exoplanets and stable spectroscopic observations at the Very Large Telescope in Chile to study starlight as it passes through each planet’s atmosphere.
“Because they are gaseous and hot, their atmospheres are very stretched out,” Demangeon said. “Thus, they are easier to observe and study than smaller or colder planets.”
Future telescopes will also be able to see more detail in the atmospheres of exoplanets, including rocky Earth-like planets, to unravel the mysteries of unusual worlds scattered across the galaxy.
