Researchers utilizing NASA’s James Webb Space Telescope have captured striking observations of HD 80606 b, a gas giant four times the mass of Jupiter. The planet is distinguished by an exceptionally elliptical orbit that brings it precariously close to its Sun-like host star. The team is presenting their preliminary findings this Tuesday at the 248th meeting of the American Astronomical Society in Pasadena, California.
“Hot Jupiters are already among the most extreme exoplanets we know of, but HD 80606 b is an outlier even within that group,” explained Tiffany Kataria, the study’s principal investigator at NASA’s Jet Propulsion Laboratory. “While we typically view hot Jupiters as giants permanently situated near their stars, the highly eccentric orbit of this planet creates a completely different dynamic.”
Webb’s data reveals that as the planet makes its closest approach, temperatures skyrocket by 1,100 degrees Fahrenheit. Such radical thermal swings can trigger real-time changes in an exoplanet’s atmospheric chemistry and cloud formations. Because of these volatile conditions, the research team views HD 80606 b as an ideal laboratory for studying these rapid transitions using Webb’s high-precision instruments.
This artist’s concept shows exoplanet HD 80606 b being “roasted” as its orbit approaches periastron, the point at which it is closest to its host star, which is similar to our Sun. Artwork: NASA, ESA, CSA, Joseph Olmsted (STScI)
“Studying a planet like HD 80606 b is highly efficient,” said Laura C. Mayorga, co-investigator and astronomer at the Johns Hopkins Applied Physics Laboratory. “Its unique orbit—and the resulting swings in temperature and chemistry—allows us to collect data under diverse conditions in just a few hours, which we can then apply to other hot Jupiters or more conventional exoplanets.”
The team utilized spectroscopy—the analysis of light split into component colors to determine physical properties—via Webb’s Mid-Infrared Instrument (MIRI). They tracked the planet before, during, and after periastron (its closest approach), including a secondary eclipse where the planet passed behind its star. The timing of this observation was meticulously planned to align the planet’s 111-day orbit with the telescope’s specific observational constraints relative to Earth’s position.
While the team has only begun analyzing the expansive dataset, the results are already striking. “Webb has revealed that the temperature increase was even more extreme than what we had anticipated from previous Spitzer data,” Kataria noted.
HD 80606 b, often referred to as the “roasted exoplanet,” was first studied by the now-retired Spitzer Space Telescope. Spitzer’s infrared observations provided the foundation that suggested more detailed spectroscopic data from Webb would be invaluable.
“Spitzer did amazing work, and Webb is building on that legacy by allowing us to isolate specific chemical signatures like carbon dioxide and methane,” said Ryan Challener, co-author and research associate at the Cornell Center for Astrophysics and Planetary Science. “We are just beginning to decipher the wealth of information Webb is providing.”