UAE scientist on team behind James Webb’s astronomy breakthrough

NASA’s James Webb Space Telescope has captured a stunningly detailed rainbow of near-infrared starlight filtered through the atmosphere of a hot gas giant 700 light-years away. The transmission spectrum of exoplanet WASP-39b, based on a single set of measurements made using Webb’s near-infrared spectrograph and analyzed by dozens of scientists, represents a hat trick among the first: the first official scientific observation of an exoplanet by Webb; the first detailed spectrum of exoplanets covering this near-infrared color range; and the first indisputable evidence of carbon dioxide in the atmosphere of a planet orbiting a distant star. The results point to Webb’s ability to spot key molecules like carbon dioxide in a wide variety of exoplanets – including smaller, colder and rockier planets – providing information on composition, formation and evolution. planets across the galaxy.

WASP-39 b is a hot gas giant with a mass about a quarter that of Jupiter (about the same as Saturn) and a diameter 1.3 times larger than Jupiter. Its extreme swelling is partly related to its high temperature (about 1,600 degrees Fahrenheit or 900 degrees Celsius). Unlike the cooler, more compact gas giants in our solar system, WASP-39b orbits very close to its star – only about one-eighth the distance between the Sun and Mercury – completing one circuit in just over four Earth days. The discovery of the planet, reported in 2011, was made based on ground-based detections of the subtle and periodic attenuation of light from its host star as the planet transits or passes in front of the star.

Presence of carbon dioxide

Previous observations from other telescopes, including NASA’s Hubble and Spitzer Space Telescopes, have revealed the presence of water vapor, sodium and potassium in the planet’s atmosphere. Webb’s unparalleled infrared sensitivity also confirmed the presence of carbon dioxide on this planet.

Transiting planets like WASP-39b, whose orbits we observe from the edge rather than the top, can provide researchers with ideal opportunities to probe planetary atmospheres. During a transit, some of the starlight is completely eclipsed by the planet (causing the global dimming) and some is transmitted through the planet’s atmosphere.

Blecic, along with Ian Dobbs-Dixon, PI of the Exoplanet Research Group at NYUAD, specialize in using these transit observations to unlock the multitude of secrets hidden inside exoplanet atmospheres: their temperatures, their compositions, their dynamics and their clouds. They are particularly interested in the chemical structure of the atmosphere. Since different gases absorb different combinations of colors, it is possible to analyze small differences in the brightness of transmitted light across a spectrum of wavelengths to determine exactly what an atmosphere is made of.

In the case of WASP-39b, the combination of its puffy atmosphere and frequent transits made it an ideal target for transmission spectroscopy, leading to it being chosen for observations during the first months after launch. of the JWST. The research team used Webb’s Near Infrared Spectrograph (NIRSpec) for their observations of WASP-39b. In the resulting spectrum of the exoplanet’s atmosphere, a small hill between 4.1 and 4.6 microns presents the first clear and detailed evidence of carbon dioxide ever detected on a planet outside the solar system. No observatory has ever measured such subtle differences in the brightness of so many individual colors in the 3-5.5 micron range in an exoplanet transmission spectrum before.

The detection of such a clear carbon dioxide signal on WASP-39b bodes well for detecting atmospheres on smaller, Earth-sized planets,” said Natalie Batalha of the University of California, Santa. Cruz, who leads the team.

“Carbon dioxide molecules are sensitive tracers of the history of planet formation,” said Mike Line of Arizona State University, another member of this research team.

This NIRSpec prism sighting of WASP-39b is just part of a larger investigation that includes sightings of the planet using multiple Webb instruments, as well as sightings of two other transiting planets. Blecic is a co-investigator on all these projects and actively participates in modeling their atmospheres.

The survey, part of the Early Release Science program, was designed to provide the exoplanet research community with solid Webb data as soon as possible.

“The goal is to quickly analyze Early Release Science observations and develop open source tools that the scientific community can use,” explained Vivien Parmentier, also a co-researcher from the University of Oxford.

“This allows for contributions from around the world and ensures that the best possible science will come out of the next few decades of observations,” she added.


Blecic, in collaboration with Dobbs-Dixon and Mohamad Ali-Dib, NYUAD researcher and co-investigator on another JWST proposal, is currently developing comprehensive atmospheric models to analyze exoplanetary atmospheres in multiple dimensions using JWST observations. Their models are the first in the exoplanet community that combine intrinsic physical principles and JWST observations with advanced machine learning techniques and GPU architecture to gain insight into complex 3D atmospheric structure. These state-of-the-art models would not reach their full potential without the high resolution and wavelength coverage of observations that only became available with JWST.

Solve the mysteries of space

The James Webb Space Telescope is the world’s first space science observatory. Webb will solve the mysteries of our solar system, look beyond distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.

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