We just got the most detailed view of an exoplanet’s atmosphere — and it’s active

(ORDO NEWS) — WASP-39b, a gas giant about 700 light-years away, has turned out to be a true exoplanet treasure.

Earlier this year, WASP-39b was the first to detect carbon dioxide in the atmosphere of a planet outside the solar system.

Now a deep analysis of data from the James Webb Space Telescope (JWST) has given us an absolute goldmine of information: the most detailed look at an exoplanet’s atmosphere.

The results include information on WASP-39b clouds, the first-ever direct detection of photochemistry in an exoplanet’s atmosphere, and a near-complete inventory of atmospheric chemistry that reveals tantalizing hints about the exoplanet’s formation history.

These groundbreaking discoveries were published in five papers in the journal Nature and pave the way for the possible discovery of chemical signatures of life beyond the planet. Solar system.

“These early observations are the harbinger of more amazing scientific discoveries. JWST,” says astrophysicist Laura Kreidberg, director of the Max Planck Institute for Astronomy in Germany.

“We tested the telescope to check its performance, and it turned out to be almost flawless – even better than we had hoped. .”

Ever since the first exoplanets were discovered in the early 1990s, we have been eager to learn more about these worlds orbiting alien stars.

But the difficulties were not easy. Exoplanets can be very small and very distant. Most of them we have never even seen: we only know of their existence based on the effect they have on their host stars.

One such effect occurs when an exoplanet passes between us and a star. an event known as a transit. This causes the starlight to dim slightly; periodic darkening phenomena suggest the presence of a body in orbit. We can even tell how big this orbiting body is based on the obscuration and gravitational pull on the star.

And there is something else we can say based on transit data. As starlight passes through the atmosphere of a transiting exoplanet, it changes. Some wavelengths in the spectrum are dimmer or brighter, depending on how molecules in the atmosphere absorb and re-emit light.

The signal is weak, but with a sufficiently powerful telescope and a set of transits, the change in absorption and emission characteristics in the spectrum can be deciphered to determine the composition of the exoplanet’s atmosphere.

JWST is the most powerful space telescope ever launched. Using three of his four instruments, he obtained detailed infrared spectra of the star WASP-39. The scientists then proceeded to analyze the color codes.

The first step was a census of the molecules present in the atmosphere of WASP-39b. In addition to the aforementioned carbon dioxide, the researchers found water vapour, sodium, and carbon monoxide. No methane was detected, which means that the metallicity of WASP-39b is higher than that of Earth.

The abundance of these elements is also significant. In particular, the carbon to oxygen ratio suggests that the exoplanet formed much farther away from its host star than its current close position, occupying a four-day orbit.

And modeling and observational data suggest that the sky of the exoplanet is populated by broken clouds – not from water, but from silicates and sulfites.

Finally, observations revealed the presence of a compound called sulfur dioxide. Here in the solar system, on rocky worlds like Venus and Jupiter’s moon Io, sulfur dioxide is the result of volcanic activity.

But on gas worlds, sulfur dioxide has a different story of origin: it is formed when hydrogen sulfide breaks down under the action of light into its constituent parts, and the resulting sulfur is oxidized.

The chemical reactions caused by photons are known as photochemistry, and they are important for habitability, atmospheric stability, and aerosol formation.

To be clear, WASP-39b is unlikely to be habitable for life as we know it for a range of reasons, including but not limited to scorching temperatures and gas composition, but photochemistry detection has implications for studying other worlds’ atmospheres and understanding the evolution of WASP itself. -39b.

Planetary scientists have been preparing for years for the understanding of atmospheres that JWST was expected to provide. With the first detailed analysis of an exoplanet’s atmosphere, it looks like the space telescope will live up to its promises.

In addition, the teams involved in this study are preparing documentation so that other scientists can apply their methods to future JWST exoplanet observations.

We may not detect signs of life in an exoplanet’s atmosphere with JWST – an even more powerful telescope may be needed to provide this level of fine detail – but with the analysis of WASP -39b, this discovery is becoming more and more enticingly accessible.

“Data like this,” says astronomer Natalie Batalha of the University of California at Santa Cruz, “is a game changer.”


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