His future other worlds appear bright thanks to the James Webb Space Telescope. In recently published findings from the Webb Early Release Science program, researchers have obtained the first detailed chemical profile of an exoplanet’s atmosphere and have even come to understand the possible shapes of alien clouds in the planet’s skies.
The exoplanet in question is WASP-39b, a Saturn-sized gas giant orbiting close to its star, about 700 light-years from Earth. Scientists have studied WASP-39b in the past using the Hubble and Spitzer space telescopes to identify water in the exoplanet’s atmosphere in 2018, while Webb first detected carbon dioxide on the planet in August.
But the new Webb observations released Tuesday are a much broader and more detailed view of WASP-39b’s atmosphere, and even provide clues as to how such a large planet ended up orbiting closer to its star than Mercury does to the Sun. us. Additionally, the new findings fulfill the primary goal of the Webb Early Release Science program, which was to test and demonstrate what the new flagship space telescope is really capable of.
“Without this program, we probably wouldn’t have been able to do this kind of detailed analysis on a planet as quickly and efficiently as we did,” Adina Feinstein, a graduate student at the University of Chicago and lead author of a forthcoming paper on the new Webb results. says Inverse. “And the accuracy we’re getting is kind of beyond our wildest dreams.”
What’s new – While previous studies detected water and carbon dioxide in WASP-39b’s atmosphere, the new research revealed a wider range of chemicals. Water vapor and carbon dioxide were found, but also carbon monoxide, sodium, potassium and, most importantly, sulfur dioxide, which has never been detected in an exoplanet atmosphere.
“What’s really interesting about sulfur dioxide is that the only way to understand it in a planetary atmosphere is through a process called photochemistry,” says Feinstein. “So this is one of the first pieces of evidence we have of a star-planet interaction, where because the planet is so close to its star and so irradiated, you can create these kinds of species.”
The findings also help explain how WASP-39b came to orbit so close to its star, he adds. The new Webb data show a low carbon-to-oxygen ratio in the exoplanet’s atmosphere, meaning there are far more oxygen-containing molecules like water vapor than carbon-containing molecules like methane, which didn’t show up at all in the new observations.
Because carbon-containing molecules tend to accumulate in planets more when they are farther away from a star, according to Feinstein, with less carbon accumulating if that planet migrates closer to a star, scientists now believe that WASP-39b it formed very far from its star, not anywhere near where it is today in its very short orbital period, and then migrated inwards,” he says.
As powerful as the Webb telescope is, it cannot directly image a planet as distant as WASP-39b and instead detects information carried by its star’s light as it passes through the exoplanet’s atmosphere as the planet passes in front of its star from Webb’s star. point of EXCELLENCE. But this information provides more than the chemical fingerprints of WASP-39b’s atmosphere. It may also help scientists paint a picture of what the exoplanet would look like if humans could visit it. Evidence from Webb’s new data shows, for example, “that WASP-39b has what are known as patchy clouds, which are very similar to what we see here on Earth, where we have areas of high cloud and areas of low cloud ,” says Feinstein. This is some of the first, tentative evidence of this kind of cloud structure on an exoplanet.”
The results are detailed in five papers that are still pending publication but are publicly available on the academic preprint server arxiv.org.
How did they do it? — The basics of the new WASP-39b observations are tried and true: scientists point a telescope at a distant star and wait for an exoplanet to pass between the star and the telescope, “transiting” the star. The telltale dip in star brightness caused by a passing exoplanet is one method exoplanet hunters use to find these alien worlds in the first place, but scientists can also study these exoplanets by observing starlight that passes through the planet’s atmosphere during a transit.
Webb can supercharge such observations of exoplanet atmospheres thanks to the enormous scale and power of the new telescope. With a primary mirror 21 feet in diameter, compared to Hubble’s eight feet, and Spitzer’s 2.8 feet, Webb can simply gather and magnify much more light, seeing and revealing more.
But the record-breaking visuals are only part of the story. Webb’s highly tuned instruments, completed as part of the Early Release Science program, were able to analyze information inaccessible and out of focus for Hubble and Spitzer.
It was the Near-Infrared Imager and Slitless Spectrograph, or the NIRISS instrument, for example, that detected the carbon-to-oxygen ratio that tells astronomers so much about the origin of WASP-39b.
“Hubble didn’t have the resolution we needed to be able to resolve this feature,” says Feinstein.
Meanwhile, it was Webb’s Near Infrared Spectrometer, or NIRSpec, that detected the sulfur dioxide that indicates active photochemistry taking place in WASP-39b.
Spectrometers like NIRSpec and NIRISS break up light into wavelengths, and since scientists know which molecules absorb light at different wavelengths, the resulting spectrum tells scientists which molecules are or aren’t present in an exoplanet atmosphere. It turns out that specializing in infrared light observation, which Webb does, is better for this kind of exoplanet spectrometry than a more general telescope like Hubble, which observes in ultraviolet, visible, and a bit of infrared light.
So far, Webb’s early observations have outperformed scientists like Feinstein.
“We had to go back and forth between whether we believe the data,” he says, “or whether we believe our older models.”
What’s next – As part of the Early Release Science program, the new findings are intended to help scientists predict what they can expect from Webb in the coming years.
In the short term, according to Feinstein, this means more work on WASP-39b and other exoplanets coming from the Early Release Science program data. And then there are also the exoplanet observations currently taking place as part of Webb’s first year of official science observations, the first cycle, which includes fascinating worlds like the TRAPPIST-1 planets, small rocky worlds about 40 light-years from Earth.
In the long run, these observations will only become more detailed, helping scientists understand the true range of diversity of worlds outside our Solar System and in turn helping us understand our own place in the universe.
“We’re really starting to get a sense of the demographics of what exoplanet atmospheres look like,” says Feinstein. “It really is like the dawn of a new era for exoplanet atmospheres.”