Abu Dhabi: An Abu Dhabi-based researcher working with a team of international scientists has helped uncover the first chemical portrait of hot Saturn, a distant planet orbiting a star that is 700 light years away from Earth.
Jasmina Blecic, a scientist at NYU Abu Dhabi’s Center for Astro, Particle and Planetary Physics, is part of the James Webb Space Telescope (JWST) international mission led by NASA, in collaboration with the European Space Agency and the Canadian Space Agency. The mission trained four highly sensitive instruments aboard the JWST 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, to reveal an unprecedented view into a chemical portrait of the planet’s skies.
Full picture
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, Blecic said in a statement sent by the NYU Abu Dhabi on Wednesday.
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.
Clarity of observation
“The clarity of the observations which came from these instruments, before any data cleaning was performed, was mind blowing! The raw data looked polished, as if we already performed a heavy lifting 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,” Blecic, who is also member of the only Exoplanetary Atmospheres research group in UAE led by Ian Dobbs-Dixon.
“The clarity of the observations which came from these instruments, before any data cleaning was performed, was mind blowing! The raw data looked polished, as if we already performed a heavy lifting 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,” Blecic, who is also member of the only Exoplanetary Atmospheres research group in UAE led by Ian Dobbs-Dixon.
New investigations
These findings 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.
Exoplanet photochemistry
“This is the first time we see concrete evidence of photochemistry on exoplanets,” said Shang-Min Tsai, a researcher at the University of Oxford and the author of the paper explaining the origin of sulphur 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,” Blecic added.
The resulting improvements in modelling will help interpret potential signs of life in the future, when we observe smaller, potentially habitable, terrestrial-sized planets. With an estimated temperature of 1,600 degrees Fahrenheit, or 900 degrees Celsius, and an atmosphere made mostly of hydrogen, WASP-39 b is, however, not believed to be habitable.
Atmospheric findings
Other atmospheric constituents detected by JWST include sodium, potassium, and water vapour, confirming previous observations, as well as additional water features, at longer wavelengths, that have not been seen before.
“We, again, saw, and now confirmed with multiple JWST instruments, carbon dioxide. Carbon dioxide is ubiquitous in our solar system. It is also the most abundant chemical species in the atmospheres of terrestrial, but inhabitable planets like Venus and Mars, both sitting, together with Earth, within the boundaries of our Sun’s habitable zone. This first indisputable detection of this molecule in an exoplanetary atmosphere has, thus, opened new frontiers for future JWST observations of planets laying within the habitable zones of their host stars, as it will allow us to differentiate between habitable and inhabitable worlds,” Blecic said.
The latest data also give us a hint of how clouds on WASP-39 b might look up close: a patchy, broken up cloud structure like on Earth, rather than a single, uniform blanket across the planet as we see on Venus.
Planet formation possibilities
Having such a complete roster of ingredients in an exoplanet atmosphere also gives scientists a glimpse of how this planet, and perhaps others, formed. WASP-39 b’s chemical inventory suggests its formation far away from its host star, and a history of smash-ups and mergers of smaller bodies called planetesimals that eventually created a goliath of a planet.
Capturing such a broad spectrum of WASP-39 b’s atmosphere was a scientific tour de force. The international team was numbering hundreds of independently analysed data, performing at the same time detailed inter-comparisons of their findings, yielding yet more scientific results.
“These magnificent discoveries, disclosed from the observation of a single target, demonstrated performance of the JWST instruments well beyond scientists’ expectations, establishing an exciting path for future observations, and opening a new era of exploration among the huge diversity of exoplanets within our galaxy,” Blecic said.
