Astronomers report the discovery of a giant planet and a surrounding debris disk around a young, nearby M-dwarf star called RX J0534.0-0221. The planet, named RX J0534 b, was first seen in images from the James Webb Space Telescope (JWST). The system belongs to the Beta Pictoris moving group, a collection of young stars about 18–26 million years old.

The team found the planet in JWST NIRCam images taken through a long-wavelength infrared filter (called F444W). The object appears as a point source with a signal-to-noise ratio near 17.5 at an angular separation of about 0.41 arcseconds from the star. That separation corresponds to roughly 14 astronomical units (AU), or about 14 times the Earth–Sun distance. The source was not seen in JWST’s shorter-wavelength F200W image. A ground-based follow-up 16 months later with the Large Binocular Telescope’s LMIRCam instrument (in the L′ band) re-detected the object. The two detections together show that the source moves with the star, rather than being a background object, with a statistical confidence of about 6–7 standard deviations.

From the measured brightnesses, the researchers estimate the planet’s total emitted power (its bolometric luminosity) as log10(L/L☉) = −5.48 with asymmetric uncertainties. Using so-called “hot-start” evolutionary models and the assumed system age of 18–26 million years, this luminosity corresponds to a mass of about 2.8 ± 0.5 times the mass of Jupiter and an effective temperature near 674 +57/−49 kelvin. Hot-start models assume the planet began life relatively hot and glowing; mass estimates change if the planet formed colder or by a different process, so the mass has model-dependent uncertainty.

The planet’s color between the L′ band and JWST’s F444W filter is unusual compared with simple expectations. The authors suggest this may indicate disequilibrium chemistry (chemical reactions and vertical mixing that keep the atmosphere out of chemical balance) or a higher-than-solar metallicity (more heavy elements) in the planet’s atmosphere. These conclusions are tentative because they rest on a small set of photometric points rather than a full spectrum.