Observation of undepleted phosphine in the atmosphere of a low-temperature brown dwarf

Abstract

The atmospheres of low-temperature brown dwarfs and gas giant planets are expected to contain the phosphine molecule, PH${}_3$ However, previous observations have shown much lower abundances of this molecule than predicted by atmospheric chemistry models. We report JWST spectroscopic observations of phosphine in the atmosphere of the brown dwarf Wolf 1130C. Multiple absorption lines due to phosphine are detected around 4.3 $\mu$m, from which we calculate a phosphine abundance of 0.100$\pm$0.009 parts per million. This abundance is consistent with disequilibrium atmospheric chemistry models that reproduce the phosphine abundances in Jupiter and Saturn, and is much higher than abundances previously reported for other brown dwarfs or exoplanets.

33 pages, 10 figures; accepted for publication in Science. This is the authors' version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published in Science on 2 October 2025, DOI: 10.1126/science.adu0401 (https://www.science.org/doi/10.1126/science.adu0401)

References in corpus (28)

• Gaia Data Release 3: Summary of the content and survey properties
• The chemical make-up of the Sun: A 2020 vision
• The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope I. Overview of the instrument and its capabilities
• Line and Mean Opacities for Ultracool Dwarfs and Extrasolar Planets
• Early Release Science of the exoplanet WASP-39b with JWST NIRSpec PRISM
• The CatWISE2020 Catalog
• ExoMol molecular line lists - XVI: The rotation-vibration spectrum of hot H${}_2$S
• An accurate, extensive, and practical line list of methane for the HITEMP database
• Ammonia as a tracer of chemical equilibrium in the T7.5 dwarf Gliese 570D
• ExoMol line lists VII: The rotation-vibration spectrum of phosphine up to 1500 K
• The Ages of the Thin Disk, Thick Disk, and the Halo from Nearby White Dwarfs
• PICASO 3.0: A One-Dimensional Climate Model for Giant Planets and Brown Dwarfs
• Confirmation of circumstellar phosphine
• Phosphine as a Biosignature Gas in Exoplanet Atmospheres
• A High Internal Heat Flux and Large Core in a Warm Neptune Exoplanet
• Cloud busting: enstatite and quartz clouds in the atmosphere of 2M2224-0158
• The Sonora Substellar Atmosphere Models. IV. Elf Owl: Atmospheric Mixing and Chemical Disequilibrium with Varying Metallicity and C/O Ratios
• Observations of Disequilibrium CO Chemistry in the Coldest Brown Dwarfs
• Detection of Neutral Phosphorus in the Near Ultraviolet Spectra of Late-Type Stars
• Phosphorus-rich stars with unusual abundances are challenging theoretical predictions
• Methane Emission From a Cool Brown Dwarf
• The Chemical Evolution of Phosphorus
• The Galactic Chemical Evolution of phosphorus observed with IGRINS
• The first retrieval of a substellar subdwarf: A cloud-free SDSS J125637.13-022452.4
• The Galactic Distribution of Phosphorus: A Survey of 163 Disk and Halo Stars
• Large Uncertainties in the Thermodynamics of Phosphorus (III) Oxide (P${}_4$O${}_6$) Have Significant Implications for Phosphorus Species in Planetary Atmospheres
• Unveiling the chemical fingerprint of phosphorus-rich stars I. In the infrared region of APOGEE-2
• Optical constraints on the coldest metal-poor population

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