Heaviest element ever discovered in exoplanet atmospheres is a puzzle

By Georgina Torbet October 15, 2022

When it comes to finding habitable exoplanets, the next big challenge is not just spotting exoplanets or looking at their orbits, but getting a better understanding of what conditions there might be like by analyzing their atmospheres. New tools like the James Webb Space Telescope will allow us to peer into the atmospheres of exoplanets and see what they are composed of, which can affect the planet’s surface temperature, pressure, and weather systems.

Now, astronomers using the European Southern Observatory’s Very Large Telescope (ESO’s VLT), a ground-based telescope located in Chile, have discovered the heaviest element ever in an exoplanet atmosphere. Looking at two ultra-hot gas giants called WASP-76 b and WASP-121 b, the researchers identified the element barium in their atmospheres.

Artist’s impression of an ultra-hot exoplanet as it is about to transit in front of its host star. — This artist’s impression shows an ultra-hot exoplanet, a planet beyond our Solar System, as it is about to transit in front of its host star. Using the ESPRESSO instrument of ESO’s Very Large Telescope, astronomers have found the heaviest element yet in an exoplanet’s atmosphere, barium, in the two ultra-hot Jupiters WASP-76 b and WASP-121 b. ESO/M. Kornmesser

These two planets orbit extremely close to their respective stars and thus have extremely high surface temperatures which can go over 1,000 degrees Celsius. On one of the planets, WASP-76 b, it gets so got that iron falls from the sky as rain. But the researchers were surprised to find barium high in the atmospheres of these planets because it is so heavy.

“The puzzling and counterintuitive part is: why is there such a heavy element in the upper layers of the atmosphere of these planets?” said lead author Tomás Azevedo Silva of the Instituto de Astrofísica e Ciências do Espaço (IA) in Portugal, in a statement.

“Given the high gravity of the planets, we would expect heavy elements like barium to quickly fall into the lower layers of the atmosphere,” said co-author Olivier Demangeon.

The researchers still aren’t sure what is causing this very heavy element to appear in the exoplanet atmospheres, but the fact it has been identified in not one but two different hot Jupiter atmospheres is interesting. Further research will be needed to discover where this barium came from and how it stays so high in the atmosphere.

The research is published in the journal Astronomy & Astrophysics.

Editors' Recommendations

Topics

Tech News

Georgina Torbet

Space Writer

Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…

Space

Small exoplanet could be hot and steamy according to Hubble

This is an artist’s conception of the exoplanet GJ 9827d, the smallest exoplanet where water vapour has been detected in its atmosphere. The planet could be an example of potential planets with water-rich atmospheres elsewhere in our galaxy. It is a rocky world, only about twice Earth’s diameter. It orbits the red dwarf star GJ 9827. Two inner planets in the system are on the left. The background stars are plotted as they would be seen to the unaided eye looking back toward our Sun, which itself is too faint to be seen. The blue star at upper right is Regulus, the yellow star at bottom centre is Denebola, and the blue star at bottom right is Spica. The constellation Leo is on the left, and Virgo is on the right. Both constellations are distorted from our Earth-bound view from 97 light-years away.

One of the big topics in exoplanet research right now is not just finding exoplanets but also looking at their atmospheres. Tools like the James Webb Space Telescope are designed to allow researchers to look at the light coming from distant stars and see how it is filtered as it passes by exoplanets, allowing them to learn about the composition of their atmospheres. But scientists are also using older telescopes like the Hubble Space Telescope for similar research -- and Hubble recently identified water vapor in an exoplanet atmosphere.

“This would be the first time that we can directly show through an atmospheric detection that these planets with water-rich atmospheres can actually exist around other stars,” said researcher Björn Benneke of the Université de Montréal in a statement. “This is an important step toward determining the prevalence and diversity of atmospheres on rocky planets."

Space

Astronomers discover extremely hot exoplanet with ‘lava hemisphere’

Like Kepler-10 b, illustrated above, the exoplanet HD 63433 d is a small, rocky planet in a tight orbit of its star. HD 63433 d is the smallest confirmed exoplanet younger than 500 million years old. It's also the closest discovered Earth-sized planet this young, at about 400 million years old.

Astronomers have discovered an Earth-sized exoplanet with an unusually extreme climate where one half of the planet is thought to be covered in lava. The planet HD 63433 d is tidally locked, meaning one side of it always faces its star while the other half always faces out into space, creating a huge difference in temperatures between the planet's two faces.

Like Kepler-10 b, illustrated above, the exoplanet HD 63433 d is a small, rocky planet in a tight orbit of its star. HD 63433 d is the smallest confirmed exoplanet younger than 500 million years old. NASA/Ames/JPL-Caltech/T. Pyle

Space

See the weather patterns on a wild, super hot exoplanet

This is an artist’s impression of the exoplanet WASP 121-b, also known as Tylos. The exoplanet’s appearance is based on Hubble data of the object. Using Hubble observations, another team of scientists had previously reported the detection of heavy metals such as magnesium and iron escaping from the upper atmosphere of the ultra-hot Jupiter exoplanet, marking it as the first of such detection. The exoplanet is orbiting dangerously close to its host star, roughly 2.6% of the distance between Earth and the Sun, placing it on the verge of being ripped apart by its host star's tidal forces. The powerful gravitational forces have altered the planet's shape.

When it comes to understanding exoplanets, or planets outside our solar system, the big challenge is in not only finding these planets, but also understanding what they are like. And one of the biggest factors that scientists are interested in is whether an exoplanet has an atmosphere and, if so, what it is composed of. But, just like with weather here on Earth, exoplanet atmospheres aren't static. So the Hubble Space Telescope was recently used for an intriguing observation -- comparing data from an exoplanet atmosphere that had previously been observed, to see how it changed over time.

Hubble looked at planet WASP-121 b, an extreme planet that is so close to its star that a year there lasts just 30 hours. Its surface temperatures are over 3,000 Kelvins, or 5,000 degrees Fahrenheit, which researchers predict would lead to some wild weather phenomena. As it is such an extreme planet, WASP-121 b is well-known and has been observed by Hubble several times over the years, beginning in 2016.