Active chemistry, clouds in exoplanet: Scientist
ABU DHABI: Four highly sensitive instruments on the James Webb Space Telescope (JWST) were trained on the atmosphere of a hot Saturn – a planet about as massive as Saturn orbiting a star 700 light-years away known as WASP-39 b, revealing an unprecedented view into a chemical portrait of the planet’s skies, a team of scientists from institutions worldwide and NYU Abu Dhabi (NYUAD) reported.
While previous observations detected isolated ingredients of this broiling planet’s atmosphere, the new readings provide a full menu of atoms, molecules, and even signs of active chemistry and clouds, highlights Jasmina Blecic, a scientist at NYUAD’S Center for Astro, Particle and Planetary Physics (CAP3), a member of the only Exoplanetary Atmospheres research group in UAE led by Ian Dobbs-dixon, and part of the JWST team.
JWST sees the universe in infrared light, on the red end of the light spectrum beyond what human eyes can see. This allows the telescope to pick up fingerprints of molecular species that cannot be detected in visible light. WASP-39 b was observed as it passed in front of its host star, capturing in this way the starlight filtered through the planetary atmosphere. Different molecular species present in the planetary atmosphere absorbed different parts of the stellar light, revealing the enriched chemical background of the planet envelope.
“The clarity of the observations which came from these instruments, before any data cleaning was performed, was mind-blowing!” says Blecic. “The raw data looked polished, as if we already performed a heavy liting of reducing noise and instrumental errors that we used to do with the Spitzer and Hubble telescopes, and the molecular features were noticeable from a first look,” says Blecic. These facts bode well for the capabilities of the JWST instruments to conduct investigations of smaller, rocky exoplanets, hoped for by the science team.
The suite of new discoveries is detailed in a set of five new scientific papers co-authored by Blecic, to be published this month in the journal Nature. Among the remarkable revelations is the first detection of sulphur dioxide in an exoplanet atmosphere, a molecule produced from chemical reactions triggered by high-energy photons coming from the planet’s star. On Earth, the protective ozone layer is created in a similar way.
“This is the first time we see concrete evidence of photochemistry on exoplanets,” said Shangmin Tsai, a researcher at the University of Oxford and the author of the paper explaining the origin of sulfur dioxide in WASP-39 b’s atmosphere.
“It is also the first time that we had to include higher level physics into our models so we can explain the data,” adds Blecic. The resulting improvements in modelling will help interpret potential signs of life in the future, when we observe smaller, potentially habitable, terrestrialsized planets. With an estimated temperature of 1,600 degrees Fahrenheit (900 degrees Celsius) and an atmosphere made mostly of hydrogen, WASP-39 b is, however, not believed to be habitable.