The discovery demonstrates JWST’s long-awaited capabilities to observe the atmospheres of planets outside our solar system, revealing their composition and formation histories. These results open the door to the possibility of learning about the composition of smaller rocky planets that are also thought to have carbon dioxide in their atmospheres. The results of their findings were accepted in Nature, under the title “Identification of Carbon Dioxide in an Exoplanet Atmosphere”. This is the first accepted publication detailing exoplanet observations with JWST. The gas giant exoplanet WASP-39 b was discovered in 2011 and orbits a star similar to our sun but 700 light-years away. It has a mass about that of Saturn and takes only four days to complete an orbit around its star, making it extremely hot, about 1,400 degrees Celsius. WASP-39b and other passing exoplanets will allow researchers to examine the atmospheres of these worlds. A transit is when a planet passes between a star and the observer, causing a slight decrease in starlight. For the study, Line, who is an associate professor in the School of Earth and Space Exploration, and the team used JWST’s Near Infrared Spectrometer (NIRSpec) to make observations of the planet in different wavelengths, or colors, of light. passed in front of its host star. These observations, also known as a transit spectrum, allowed the team of researchers to determine exactly what the planet’s atmosphere is made of. “I felt like a kid in a candy store when I first saw this spectrum. The fact that we can clearly see bumps and shakes – point to them and say, “Hey, that’s carbon dioxide, hey, that’s water vapor, whoa, here’s this other bump and I don’t know what it is!” — suggests enormous potential for discovery in the worlds beyond our solar system. It really is a game changer,” Line said. Understanding the composition of a planet’s atmosphere is important because it tells us something about the origin of the planet and how it evolved. “Carbon dioxide molecules are sensitive tracers of planet formation history,” Line said. “By measuring this characteristic of carbon dioxide, we can determine how much solid (carbon- and oxygen-rich ices) versus how much gaseous (hydrogen and helium) material was used to form this gas giant planet. Over the next decade, JWST will make this measurement for a variety of planets, providing insights into the details of how planets form and the uniqueness of our solar system.” The NIRSpec prism observation of WASP-39 b is just one part of a larger survey that includes observations of this planet using multiple instruments on JWST, as well as observations of two other transiting planets. The survey, part of the Early Release Science program, was designed to provide the exoplanet research community with robust JWST data as soon as possible. “The goal is to rapidly analyze the Science Early Edition observations and develop open source tools for use by the scientific community,” said Vivien Parmentier of the University of Oxford, a co-author of the study. “This allows for contributions from around the world and ensures that the best possible science will come out of the next decades of observations.” Line, along with NASA Hubble Postdoctoral Fellow Luis Welbanks and graduate student Lindsey Wiser, both in the School of Earth and Space Exploration, are leading the theoretical interpretations of the data resulting from the Early Release Science program. “This is a once in a lifetime opportunity,” Welbanks said. “For the first time in the history of the field, hundreds of people around the world are working together to learn as much as we can from these valuable observations.” “This is just the beginning. We have many more data sets to analyze from this program – and many more – in the coming months and years,” Line said. “I’m still trying to wrap my head around the fact that we’re finally getting data from JWST. I thought I would have seen this data as a graduate student a decade ago. The wait was worth it.” ASU Press Contact: Kim Baptista, 707-479-0311, [email protected] About Arizona State University Arizona State University has developed a new model for the American Research University, creating an institution committed to access, excellence and impact. ASU measures itself by those it includes, not those it excludes. As a prototype for a New American University, ASU pursues research that contributes to the public good, and ASU takes great responsibility for the economic, social, and cultural vitality of the communities that surround it. Astrobiology, Astrochemistry
