Irish scientist helps discover water vapour on exoplanet

15 Nov 2023

Illustration of exoplanet WASP-107b. Image: Klaas Verpoest, Johan Van Looveren, Achrène Dyrek, Michiel Min, Leen Decin/ESA/NASA

Prof Tom Ray of DIAS was part of a team that used data from the James Webb to unravel the composition of a gaseous exoplanet named WASP-107b.

An Irish astrophysicist is part of an international team that has discovered the presence of water vapour and other compounds on a distant exoplanet using the James Webb Space Telescope.

Prof Tom Ray of the Dublin Institute for Advanced Studies (DIAS) was part of the team that looked deeply into the cloud-covered atmosphere of WASP-107b, a gaseous exoplanet orbiting a star slightly cooler and smaller than the sun.

Observations from the James Webb, specifically from its mid-infrared instrument (MIRI), allowed them to unravel the chemical composition of its atmosphere. Other than water vapour, they found sulphur dioxide and silicate sand clouds on WASP-107b.

Published in Nature today (15 November), the study also discovered that there was no trace of the greenhouse gas methane on the planet.

“These detections provide crucial insights into the dynamics and chemistry of this captivating exoplanet,” said Ray, who is a senior professor and director of the School of Cosmic Physics at DIAS and co-principal investigator for MIRI.

“The absence of methane in its upper layers hints at a potentially warm interior. This is because a hot enough interior drives enormous convection currents which, if fast enough, can destroy the chemical equilibrium of molecules like methane.”

According to Ray, the discovery of sulphur dioxide, which makes up the odour of burnt matches, on WASP-107b came as a “major surprise” to the team.

“Previous models had predicted its absence, but new climate models of WASP-107b’s atmosphere now show that the fluffiness of the exoplanet accommodates the formation of sulphur dioxide in its atmosphere,” he explained.

“[The discovery] reshapes our understanding of planetary formation and evolution, shedding new light on our own solar system. The [James Webb] has enabled us to deeply characterise the atmosphere of an exoplanet, one that does not have any counterpart in our solar system.

“We are truly discovering new worlds,” he went on. “There have been quite a number of significant discoveries by the James Webb Space Telescope, despite it being launched only two years ago, the potential for many more is clear!”

In September, scientists from Europe and North America were able to use data from the James Webb to discover methane and carbon dioxide in the atmosphere of K2-18 b, a distant exoplanet that has long piqued the curiosity of astronomers for having the potential to sustain life.

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Vish Gain is a journalist with Silicon Republic