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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.
Separately, the JWST F200W image shows an extended structure around the star that the team interprets as a resolved debris disk. Their fits place the peak density of that disk at about 79 ± 3 AU from the star, with an inclination of roughly 56.5° ± 1.5°. If confirmed, this disk would be a useful context for understanding how the planet and any other bodies in the system formed and evolved.
Important caveats remain. The planet detection is strong at some infrared wavelengths but absent at others, and the mass and temperature rely on evolutionary models and the assumed age of the star. The atmospheric interpretation comes from colors only and will need spectra for confirmation. The debris-disk interpretation, while consistent with the images, also has uncertainties. The authors note that continued orbital monitoring and more detailed atmospheric observations will be needed to confirm these ideas and to learn how a giant planet formed around a low-mass M-dwarf, a question that is hard to answer because such stars are thought to make giant planets less easily than larger stars.