22 Nov 2022

n – also makes it a laboratory for studying the effects of radiation from host stars on exoplanets. Better knowledge of the star-planet connection should bring a deeper understanding of how these processes create the diversity of planets observed in the galaxy.

Other atmospheric constituents detected by JWST include sodium, potassium, and water vapor, confirming previous space and ground-based telescope observations as well as finding additional water features, at longer wavelengths, that haven’t been seen before.

JWST also saw carbon dioxide at higher resolution, providing twice as much data as reported from its previous observations. Meanwhile, carbon monoxide was detected, but obvious signatures of both methane and hydrogen sulfide were absent from the data. If present, these molecules occur at very low levels, a significant finding for scientists making inventories of exoplanet chemistry in order to better understand the formation and development of these distant worlds.

Capturing such a broad spectrum of WASP-39 b's atmosphere was a scientific tour de force, as an international team numbering in the hundreds independently analyzed data from four of JWST's finely calibrated instrument modes. They then made detailed inter-comparisons of their findings, yielding yet more scientifically nuanced results.

JWST views the universe in infrared light, on the red end of the light spectrum beyond what human eyes can see; that allows the telescope to pick up chemical fingerprints that can't be detected in visible light.

Each of the three instruments even has some version of the "IR" of infrared in its name: NIRSpec, NIRCam, and NIRISS.

To see light from WASP-39 b, JWST tracked the planet as it passed in front of its star, allowing some of the star's light to filter through the planet's atmosphere. Different types of chemicals in the atmosphere absorb different colors of the starlight spectrum, so the colors that are missing tell astronomers which molecules are present.

By so precisely parsing an exoplanet atmosphere, the JWST instruments performed well beyond scientists' expectations — and promise a new phase of exploration among the broad variety of exoplanets in the galaxy.

López-Morales says, "I am looking forward to seeing what we find in the atmospheres of small, terrestrial planets."