The first detection of an atmosphere on a trans-Neptunian object beyond Pluto
arXiv:2605.02243 · doi:10.1038/s41550-026-02846-1
Abstract
Trans-Neptunian objects (TNOs) in the outer Solar System are predominantly small, icy worlds long presumed to be atmosphereless except for the largest bodies. Until now, Pluto has been unique among TNOs in exhibiting a substantial atmosphere (nitrogen with trace methane and carbon monoxide) at microbar pressure levels. All other known TNOs, including ~ 1000-km-sized bodies such as Eris, Haumea, Makemake, and Quaoar, have shown no detectable atmospheres in stellar occultation observations, with surface pressure upper limits of order 1-100 nanobars. Here we report the first detection of an atmosphere around a TNO besides Pluto. A stellar occultation by the ~ 250-km-radius plutino (612533) 2002 XV93 on 10 January 2024 revealed a refractive signature, indicating the presence of a thin atmosphere. The derived surface pressure is 100-200 nanobars, i.e. approximately a hundred times lower than Pluto's and yet significantly above previous limits for other larger bodies. This discovery provides the first evidence that even a sub-1000-km TNO can retain an atmosphere, challenging current paradigms of volatile retention. Our findings indicate that a fraction of distant icy minor planets can exhibit atmospheres possibly caused by ongoing cryovolcanic activity or a recent impact event of a small icy object.
Original submitted version; 20 pages, 4 figures, 3 extended data figs. The revised and published version appears in Nature Astronomy under the title "Detection of an atmosphere on a trans-Neptunian object beyond Pluto"
References in corpus (22)
- Gaia Data Release 3: Summary of the content and survey properties
- A ring system detected around the Centaur (10199) Chariklo
- The size, shape, density and ring of the dwarf planet Haumea from a stellar occultation
- TNOs are Cool: A survey of the trans-Neptunian region V. Physical characterization of 18 Plutinos using Herschel PACS observations
- High resolution spectroscopy of Pluto's atmosphere: detection of the 2.3 m CH bands and evidence for carbon monoxide
- Measuring the Abundance of sub-kilometer sized Kuiper Belt Objects using Stellar Occultations
- Amateur telescopes discover a kilometre-sized Kuiper belt object from stellar occultation
- SORA: Stellar Occultation Reduction and Analysis
- Pluto's lower atmosphere and pressure evolution from ground-based stellar occultations, 1988-2016
- A re-assessment of the Kuiper belt size distribution for sub-kilometer objects, revealing collisional equilibrium at small sizes
- Moderate D/H Ratios in Methane Ice on Eris and Makemake as Evidence of Hydrothermal or Metamorphic Processes in Their Interiors: Geochemical Analysis
- The large Trans-Neptunian Object 2002 TC from combined stellar occultation, photometry and astrometry data
- Organized Autotelescopes for Serendipitous Event Survey (OASES): design and performance
- Stellar occultations by Trans-Neptunian Objects
- Physical properties of the trans-Neptunian object (38628) Huya from a multi-chord stellar occultation
- The trans-Neptunian object (84922) 2003 VS2 through stellar occultations
- New constraint on the atmosphere of (50000) Quaoar from a stellar occultation
- Volatile evolution and atmospheres of Trans-Neptunian Objects
- The rings of (2060) Chiron: Evidence of an evolving system
- Diffraction modelling of a 2023 March 5 stellar occultation by subkilometer-sized asteroid (98943) 2001 CC21
- Reconciling results of 2019 and 2020 stellar occultations on Pluto's atmosphere. New constraints from both the 5 September 2019 event and consistency analysis
- Detection of an extremely large impact flash on Jupiter by high-cadence multiwavelength observations