Webb telescope: Large planet with banded, cloudy atmosphere and bright sun in distance.

terrestrial sky | Webb telescope 1. close look at exoplanet atmosphere

View larger. | This is an artist’s concept of what WASP-39b might look like. NASA’s Webb Telescope has performed the most detailed analysis of this planet’s atmosphere — or of any exoplanet — to date. Image by NASA/ESA/CSA/Joseph Olmsted (STScI).

The Webb Space Telescope has just taken a close-up look at the atmosphere of a distant giant exoplanet, NASA announced Tuesday, November 22. The new profile of this distant world’s atmosphere reveals atoms, molecules, active chemistry, and clouds. Planet WASP-39b is a hot Saturn-sized gas giant orbiting very closely to its star. It is 700 light years away. While WASP-39b is not a habitable world, the results demonstrate the level of detail with which Webb will be able to study the atmospheres of many other exoplanets, including potentially habitable rocky planets like Earth.

Researchers working on the WASP-39b data have published five new articles (not yet peer-reviewed) in Nature: L. Alderson et al., Z. Rustamkulov et al., E. Ahrer et al., A. Feinstein et al. and S. Tsai et al. Three of the publications are currently in press and two are under review.

The Webb telescope reveals WASP-39b’s hot atmosphere

Astronomers have previously studied WASP-39b’s atmosphere with the Webb, Hubble, and Spitzer Space Telescopes. However, Webb’s latest analysis provides much more detail, a full menu of atmosphere ingredients. And while the planet is too distant to image directly and show details, Webb analysis even gives clues as to what its clouds look like. In fact, the data suggests that the clouds have broken up rather than a unified cloud layer.

In fact, Webb’s sophisticated instruments are able to study exoplanet atmospheres in much more detail than ever before.

Natalie Batalha, an astronomer at the University of California, Santa Cruz, co-authored all five articles and helped coordinate the research. She said:

We’ve observed the exoplanet with multiple instruments, which together provide a broad swath of the infrared spectrum and a range of chemical fingerprints previously inaccessible [this mission]. Data like this is a game changer.

New revelations

WASP-39b’s molecular and chemical profile reveals the planet’s atmosphere in unprecedented detail. These include the first detection of sulfur dioxide in an exoplanet’s atmosphere. Chemical reactions produce the sulfur dioxide, a result of the star’s intense radiation hitting the planet’s atmosphere. The radiation is indeed strong as the planet orbits eight times closer to its star than Mercury orbits our Sun. This process is particularly similar to the formation of the earth’s ozone layer.

Now, thanks to Webb, photochemistry astronomers have confirmed photochemistry on an exoplanet for the first time. As Shang-Min Tsai of Oxford University in the UK and lead author of the fifth article said:

This is the first time we’ve seen concrete evidence of photochemistry – chemical reactions triggered by energetic starlight – on exoplanets. I see this as a really promising perspective to advance our understanding of exoplanet atmospheres [this mission].

With this in mind, analyzing the photochemistry will later help astronomers find and interpret potential evidence of habitability on some other exoplanets. As Batalha noted:

Planets are formed and transformed by orbiting in the host star’s bath of radiation. On Earth, these transformations allow life to thrive.

In addition, Webb also detected carbon dioxide, carbon monoxide, sodium, potassium, and water vapor in the atmosphere of WASP-39b. However, neither methane nor hydrogen sulfide were found. So if they’re there, they must be too low for even Webb to see.

4 rectangular charts with text annotations and planet behind.
View larger. | Atmospheric composition of WASP-39b. Webb has found sulfur dioxide, carbon dioxide, carbon monoxide, sodium, potassium and water vapor in the planet’s hot atmosphere. Image by NASA/ESA/CSA/Joseph Olmsted (STScI).

WASP-39b on the way

So how did Webb observe the atmosphere of WASP-39b? It did this by observing the planet as it passed in front of its star. This is known as a transit method for detecting and studying exoplanets. As the planet passed, the star’s light filtered through the atmosphere. Webb observes the universe in ultraviolet light. So astronomers looked at the colors in the spectrum of starlight. Different chemicals absorb different colors. Against this background, the astronomers investigated what colors these are absence from the spectrum to determine which molecules are in the atmosphere of WASP-39b.

Ultimately, hundreds of researchers from around the world analyzed Webb’s data. And indeed the results were extraordinary; As Hannah Wakeford, an astrophysicist at the University of Bristol in the UK, said:

We predicted what [the telescope] would show us, but it was more precise, more diverse and more beautiful than I had actually believed.

The results also support the scientific theory that planets first begin to form as smaller planetesimals. These smaller bodies collide with each other in the early history of a solar system, gradually creating larger planets. As noted by UC Santa Cruz’s Kazumasa Ohno:

The abundance of sulfur [relative to] Hydrogen indicated that the planet may have experienced a significant accumulation of planetesimals that can provide [these ingredients] to the atmosphere. The data also show that oxygen is much more abundant in the atmosphere than carbon. This possibly indicates that WASP-39 b originally formed far away from the host star.

Searching for habitable worlds with the Webb telescope

These are exciting results not only for studying WASP-39b, but also for learning more about exoplanets in general. Especially planets that are potentially habitable. Some of the other planets that Webb is looking at and will look at are rocky worlds that more closely resemble Earth, Mars, or Venus. Webb will also be able to study the atmospheres of these planets.

Of particular interest is the TRAPPIST-1 system with no fewer than seven Earth-sized planets. Three of these planets are in the star’s habitable zone, where temperatures could allow liquid water to exist. Webb has already viewed some of these worlds, and more observations are planned. No results have been published yet, but they should certainly be interesting if they are!

This is indeed an exciting time for exoplanet research. Team member Laura Flagg, a researcher at Cornell University, said:

We will be able to see the full picture of exoplanet atmospheres. It’s incredibly exciting to know that everything is being rewritten. That’s one of the best parts of being a scientist.

Conclusion: For the first time, the new Webb telescope has analyzed the atmosphere of an exoplanet orbiting a distant star. It examined the atmosphere of the Saturn-sized WASP-39b in fantastic detail. Read more about this dazzling new work from Webb.

Sources (preprint):

(1) Early Release Science of exoplanet WASP-39b using JWST NIRSpec G395H

(2) Early Release Science of exoplanet WASP-39b using JWST NIRSpec PRISM

(3) Early Release Science of Exoplanet WASP-39b with JWST NIRCam

(4) Early Release Science of exoplanet WASP-39b with JWST NIRISS

(5) Direct evidence of photochemistry in an exoplanet atmosphere

Via the Webb Space Telescope/NASA

#terrestrial #sky #Webb #telescope #close #exoplanet #atmosphere

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