UC student uses Webb NIRSpec on gas giant

University of Cincinnati graduate student Paul Smith is part of an international team using the James Webb Space Telescope to probe the atmosphere of TOI-2031 A b, a gas giant about 901 light-years from Earth. Universe Today reported the work on May 14, 2026, citing a University of Cincinnati account published May 8. The observations used Webb’s Near-Infrared Spectrograph, or NIRSpec, during a planetary transit, when the planet crossed in front of its star from Webb’s line of sight. (uc.edu) The goal was to capture starlight filtered through the planet’s atmosphere and use that transmission spectrum to identify chemical signatures. ### Which planet did the team point Webb at? TOI-2031 A b is a confirmed gas-giant exoplanet orbiting an F-type star, according to NASA’s exoplanet catalog. NASA lists the planet at 0.8 Jupiter masses and 1.267 Jupiter radii, with an orbital distance of 0.066 astronomical units and an orbital period of 5.7 days. That places it in the “hot Jupiter” class used for giant planets that orbit very close to their stars. NASA’s Exoplanet Archive lists TOI-2031 A b as the only confirmed planet currently identified in that system. The University of Cincinnati described it as a “lonely” Jupiter-like planet for that reason. (universetoday.com) ### What did Paul Smith actually do? Paul Smith led the first-planet data analysis in the project, according to the University of Cincinnati. The university said he retrieved the initial Webb data after the team secured observing time through a competitive process in which roughly 90% of proposals do not win time. (science.nasa.gov) Smith told the university he stayed up through the night waiting for the first light curve. He said the team needed to see a “U-shaped curve” to confirm Webb had been pointed at the star during the transit window, rather than a flat line that would have meant they missed it. (exoplanetarchive.ipac.caltech.edu) ### What does NIRSpec measure during a transit? Webb’s NIRSpec instrument records near-infrared light, and in transit work that light can be used to compare the star’s spectrum before, during and after the planet passes in front of it. Universe Today and the University of Cincinnati both said the team was looking for light that passed through the planet’s atmosphere during transit. (uc.edu) Differences across wavelengths can then be used to infer which molecules absorbed the starlight. A 2024 methodological study of JWST transit spectroscopy said NIRSpec has the broadest range of configurations for exoplanet time-series observations among Webb instruments. (uc.edu) That paper said NIRSpec Prism covers about 0.6 to 5.3 microns, a range widely used for atmospheric studies of transiting planets. ### What chemicals were they looking for? Smith told the University of Cincinnati that the atmosphere is expected to be similar to Jupiter’s, with hydrogen and helium dominant, along with water and carbon dioxide. Neither the university release nor the Universe Today report said the team had published a peer-reviewed atmospheric detection paper for TOI-2031 A b. (universetoday.com) Both accounts described the work as part of a broader effort to study giant exoplanet atmospheres and formation pathways. Universe Today said the observations were part of Webb Cycle 4 General Observation program GO-9025, titled “The Warm Jupiter Opportunity for Understanding Giant Exoplanet.” The report said researchers from 20 institutions are involved in the collaboration. (arxiv.org) ### Why is this one planet useful to study? The University of Cincinnati said Smith and collaborators are studying five distant gas giants to compare their atmospheres and examine why so many giant planets end up close to their stars. Smith said the group is trying to understand “formation and migration pathways” for big planets — where they formed and how they moved inward. (uc.edu) In April 2026, the team presented findings on TOI-2031 A b at the American Astronomical Society’s “Exoplanet Atmospheres 2026” meeting in Denver, according to the university and Universe Today. (universetoday.com) The next public milestone is likely a formal paper or additional conference results tied to the GO-9025 program and the wider comparison sample of gas giants the team is analyzing. (uc.edu)