The Webb telescope reveals a noxious atmosphere on a planet 700 light years away

Astrophysicists on Earth are there are no strangers to WASP-39b, an exoplanet orbiting a star about 700 light-years from Earth, although it has never been seen directly. Now the Webb Space Telescope has offered a new look at this distant world: Its observations have revealed the recipe list for the planet’s toxic atmosphere.

WASP-39b is a gas giant with the mass of Saturn and the size of Jupiter, but it orbits its star at about the same distance that Mercury is from the Sun, making the exoplanet very, very hot. The exoplanet was opened in 2011; earlier this year, Webb Telescope observations revealed carbon dioxide that hides in its atmosphere.

More molecules and chemical compounds have already been identified, including evidence of water, sulfur dioxide, carbon monoxide, sodium and potassium. The findings are under review for publication and available now on the arXiv preprint server.

“This is the first time we’ve seen concrete evidence of photochemistry — chemical reactions initiated by energetic starlight — on exoplanets,” said Shang-Min Tsai, a researcher at the University of Oxford and lead author of the paper explaining the presence of sulfur dioxide in the atmosphere of the planet, in a European Space Agency publication. “I see this as a really promising prospect for advancing our understanding of exoplanet atmospheres with [this mission].”

It’s no small feat to smell the chemicals floating in the atmosphere of a distant world. The closest confirmed exoplanet is 24.9 trillion miles away. Yet Webb was able to spot such infinitesimal molecules in WASP-39b.

Webb watched the planet, waiting for it to pass in front of the host star; when this happened, the star’s light illuminated the planet from behind. Webb captured infrared wavelengths of this light, and scientists can infer which chemicals are present in the atmosphere based on the wavelengths of light they absorb.

Webb’s capabilities have broader implications for understanding the diversity of exoplanets in our galaxy, with an eye toward their potential habitability. With its extreme heat and gaseous composition, WASP-39b is certainly inhospitable to life as we know it, but it demonstrates the kind of molecular-level analysis Webb can apply to distant worlds.

“I look forward to seeing what we find in the atmospheres of small Earth-type planets,” said Mercedes López-Morales, an astronomer at the Center for Astrophysics | Harvard & Smithsonian and co-author of the recent work, in the ESA publication.

The data presented to the researchers that chemicals in a planet’s atmosphere may be broken up into clouds rather than evenly distributed throughout its atmosphere. And based on the relative abundance of chemicals in the atmosphere, the researchers believe that WASP-39b arose from the accretion of planetesimals over time.

Although we don’t know where Webb will aim its infrared look then we know that at some point more exoplanets will be prosecuted. Webb has already studied the atmospheres of rocky planets in the TRAPPIST-1 system and may return to the system in due course. You can keep up with the latest Webb goals here.

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