NASA’s Webb Catches Exoplanet Getting Roasted

One extremely “well-done” gas giant is on the menu, according to new results from researchers analyzing observations made by NASA’s James Webb Space Telescope. The target is HD 80606 b, a planet roughly four times the mass of Jupiter with an extremely elongated orbit that takes it dangerously close to its host star before swinging far away again.

The research team is presenting its findings and preliminary analysis on Tuesday at the 248th meeting of the American Astronomical Society in Pasadena, California.

“Hot Jupiters are already among the most extreme exoplanets we know, but even within that category, HD 80606 b stands out,” said Tiffany Kataria, principal investigator of the study at NASA Jet Propulsion Laboratory in Southern California. “We usually think of hot Jupiters as gas giants locked very close to their stars, but this planet’s highly eccentric orbit creates a completely different kind of environment.”

As the planet plunges toward its star, observations from NASA’s Webb telescope show its temperature rapidly increasing by about 1,100 degrees Fahrenheit. Earlier studies have suggested that such extreme temperature swings can dramatically reshape an exoplanet’s atmospheric chemistry and cloud structure in real time. The team notes that HD 80606 b provides a rare natural laboratory for observing these rapid changes directly.

“Observing a planet like HD 80606 b is especially efficient because its unusual orbit produces dramatic shifts in temperature and chemistry that we can capture within a short observational window and then apply to understanding other hot Jupiters,” said Laura C. Mayorga, co-investigator on the study at the Johns Hopkins Applied Physics Laboratory.

Measurements of temperature and atmospheric composition were obtained through spectroscopy, a technique that splits light into its component wavelengths to reveal details about chemical makeup, motion, and physical conditions. The team used Webb’s MIRI (Mid-Infrared Instrument) to observe HD 80606 b continuously before, during, and after its periastron — the point in its orbit where it passes closest to its star. During this event, the planet also briefly passed behind the star from Webb’s perspective, producing a secondary eclipse.

Scheduling these observations required long-term planning due to the planet’s highly elliptical 111-day orbit, as well as operational constraints on where Webb can point at different times of the year depending on Earth’s position around the Sun.

Researchers say they are only beginning to analyze the full richness of the dataset, but the temperature changes are already strikingly clear.

“Webb has shown that the planet’s heating is even more extreme than we expected based on Spitzer data,” said Kataria.

The planet was already informally known as the “roasted exoplanet” and even featured in NASA’s popular science outreach materials. The now-retired Spitzer Space Telescope previously provided early infrared observations of HD 80606 b, laying the foundation for Webb’s much more detailed spectroscopic follow-up.

“Spitzer did incredible pioneering work on this planet, and Webb is now building on that legacy by allowing us to identify specific molecules such as methane and carbon dioxide,” said Ryan Challener, co-author and research associate at the Cornell Center for Astrophysics and Planetary Science. “There’s a huge amount of information in this dataset — we’re only at the beginning of understanding what it reveals.”

The NASA’s James Webb Space Telescope is the world’s leading space science observatory. It studies the origins of the universe, distant worlds, and the fundamental physics shaping cosmic evolution. Webb is an international mission led by NASA in partnership with the European Space Agency and the Canadian Space Agency.

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