Astronomers discover heaviest element ever found in exoplanet atmospheres CNN

Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news about fascinating discoveries, scientific advances and more.

CNN
—

Astronomers have spotted an unexpected chemical element high in the atmospheres of two sizzling exoplanets, where liquid iron and gems rain from the sky.

Orbiting separate stars beyond our solar system, the two exoplanets are ultra-hot gas giants called WASP-76b and WASP-121b. Astronomers used the European Southern Observatory’s Very Large Telescope to detect high-altitude barium in each exoplanet’s atmosphere.

Barium is the heaviest element ever detected in an exoplanet’s atmosphere. The journal Astronomy & Astrophysics published a study Thursday detailing the discovery.

With each revelation, WASP-76b and WASP-121b seem stranger to scientists.

“The confusing and counterintuitive part is: Why is there such a heavy element in the upper layers of these planets’ atmospheres?” said the study’s lead author Tomás Azevedo Silva, a PhD student at the University of Porto and the Institute of Astrophysics and Space Sciences in Portugal, in a statement.

“It was kind of an ‘accidental’ discovery. We weren’t expecting or looking for barium in particular and needed to verify that this is indeed from the planet as it had never been seen on an exoplanet before.”

Both exoplanets are similar in size to Jupiter, the largest planet in our solar system, but they have incredibly hot surface temperatures well in excess of 1,832 degrees Fahrenheit (1,000 degrees Celsius).

The rising temperatures on WASP-76b and WASP-121b are due to the fact that both planets are close together to its host star and completes a single orbit in about a day or two.

WASP-121b was first discovered in 2015 and is about 855 light-years from Earth. The exoplanet has a luminous water vapor atmosphere, and the strong gravitational pull of the star it orbits deforms it into the shape of a soccer ball.

The planet is tidally dependent, meaning that the same side of the planet always faces the star. This is similar to how our moon orbits the earth. On the daytime side, temperatures start at 4,040 F (2,227 C) in the lowest layer of the atmosphere and reach 5,840 F (3,227 C) in the top layer.

Scientists first spotted WASP-76b in 2016. It orbits a star in the Pisces constellation, 640 light-years from Earth. This exoplanet is also tidal, so temperatures on its dayside toward the star exceed 2,426 °C (4,400 °F).

The sizzling nature of exoplanets has given them seemingly unusual features and weather like something out of science fiction. Scientists believe that liquid iron is raining down from the sky on WASP-76b, while metal clouds and liquid gems are forming on WASP-121b.

The detection of barium in the upper atmosphere of each planet surprised researchers. The element is 2 1/2 times heavier than iron.

“Given the high gravity of the planets, we would expect heavy elements like barium to fall quickly to the lower layers of the atmosphere,” said study co-author Olivier Demangeon, a postdoctoral fellow at the University of Porto and the Institute of Astrophysics and Space Sciences in Porto Portugal, in a statement.

The finding of barium in the atmospheres of both exoplanets could indicate that ultra-hot gas giants have even more unusual features than previously thought.

On Earth, barium appears as a bright green color in the night sky when fireworks are set off. However, scientists are unsure what natural process causes the heavy element to appear so high in the atmospheres of these gas giants.

The research team used the ESPRESSO instrument or Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations installed in the Very Large Telescope in Chile to study starlight as it streams through each planet’s atmosphere.

“Because they are gaseous and hot, their atmospheres are very expanded,” Demangeon said, “and are therefore easier to observe and study than those of smaller or cooler planets.”

Future telescopes will also be able to spy more details in the atmospheric layers of exoplanets, including rocky Earth-like planets, to unlock the mysteries of unusual worlds across the galaxy.