“Spectacular discovery”. The James Webb Telescope detects CO2 around an exoplanet.

Launched at the end of 2021 by NASA, the new James Webb space telescope has delivered a spectacular scientific result. For the first time, carbon dioxide has been clearly detected in the atmosphere of an exoplanet.

The images released by NASA are taken from observations by a James Webb Telescope tool that observes the near infrared, a field invisible to the naked eye. They have been adapted to draw illustrations visible to the human eye.

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Scientists from the University of Geneva (UNIGE), the University of Bern (UNIBE) and the National Research Center (PRN) PlanetS took part in this discovery. These results will be published next week in the journal Nature, UNIGE said in a press release on Thursday.

Exoplanet WASP-39b is a hot gas giant transiting in front of its star. The latter, similar to the Sun, is located 700 light years from Earth. When a planet passes right in front of its star, some of the light from the star passes through the planet’s atmosphere before reaching the telescope.

Fingerprints

“The atmosphere then filters certain colors more than others, this depending on the material that composes it, its thickness and the presence or not of clouds”, explains Monika Lendl, co-author of the study, professor at the from the UNIGE Department of Astronomy and member of the PRN PlanetS.

‘By using the James-Webb telescope to break light down into its colours, we can identify characteristic ‘fingerprints’ of different gases and determine the composition of the atmosphere. Using the near-infrared spectrograph (NIRSpec) of the James-Webb telescope, the research team was able to detect the fingerprint of carbon dioxide in the light passing through WASP-39b’s atmosphere.

conducive to life

“As soon as we saw the data, it was clear that we were dealing with a spectacular discovery”, explains Dominique Petit dit de la Roche, researcher at UNIGE, co-author of the study and member of the PRN PlanetS. “This is the first time that carbon dioxide has been clearly detected on a planet outside the solar system,” adds the researcher.

Understanding the composition of a planet’s atmosphere helps to better understand the origin of the planet and its evolution. By clearly detecting the presence of CO2 in the atmosphere of distant exoplanets, an essential step in the search for worlds suitable for life has been taken.

A $10 billion engineering gem, the James Webb Telescope was launched into space about seven months ago, and is 1.5 million kilometers from Earth. The telescope began its scientific work in June 2022.

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