Silicate clouds and a circumplanetary disk in the YSES-1 exoplanet system

Hoch, K. K. W.; Rowland, M.; Petrus, S.; Nasedkin, E.; Ingebretsen, C.; Kammerer, J.; Perrin, M.; D'Orazi, V.; Balmer, W. O.; Barman, T.; Bonnefoy, M.; Chauvin, G.; Chen, C.; De Rosa, R. J.; Girard, J.; Gonzales, E.; Kenworthy, M.; Konopacky, Q. M.; Macintosh, B.; Moran, S. E.; Morley, C. V.; Palma-Bifani, P.; Pueyo, L.; Ren, B.; Rickman, E.; Ruffio, J.-B.; Theissen, C. A.; Ward-Duong, K.; Zhang, Y.

doi:10.1038/s41586-025-09174-w

Published July 24, 2025 | Version Supplemental material

Journal Article Open

Silicate clouds and a circumplanetary disk in the YSES-1 exoplanet system

1. Space Telescope Science Institute
2. The University of Texas at Austin
3. Goddard Space Flight Center
4. Diego Portales University
5. Millennium Nucleus on Young Exoplanets and their Moons (YEMS), Santiago, Chile
6. Max Planck Institute for Astronomy
7. Trinity College Dublin
8. Johns Hopkins University
9. European Southern Observatory
10. University of Rome Tor Vergata
11. University of Arizona
12. Grenoble Alpes University
13. San Francisco State University
14. Leiden University
15. University of California, San Diego
16. University of California, Santa Cruz
17. Observatoire de la Côte d'Azur
18. LESIA, Observatoire de Paris, Univ PSL, CNRS, Sorbonne Univ, Univ de Paris, Paris, France
19. Smith College
20. California Institute of Technology

Young exoplanets provide an important link between understanding planet formation and atmospheric evolution. Direct imaging spectroscopy allows us to infer the properties of young, wide-orbit, giant planets with high signal-to-noise ratio. This allows us to compare this young population with exoplanets characterized by transmission spectroscopy, which has indirectly revealed the presence of clouds, photochemistry and a diversity of atmospheric compositions. Direct detections have also been made for brown dwarfs, but direct studies of young giant planets in the mid-infrared were not possible before James Webb Space Telescope. With two exoplanets around a solar-type star, the YSES-1 system is an ideal laboratory for studying this early phase of exoplanet evolution. Here we report the direct observations of silicate clouds in the atmosphere of the exoplanet YSES-1 c through its 9–11 µm absorption feature, and the first circumplanetary disk silicate emission around its sibling planet, YSES-1 b. The clouds of YSES-1 c are composed of either amorphous iron-enriched pyroxene or a combination of amorphous MgSiO3 and Mg2SiO4, with particle sizes of ≤0.1 μm at 1 millibar pressure. We attribute the emission from the disk around YSES-1 b to be from submicron olivine dust grains, which may have formed through collisions of planet-forming bodies in the disk.

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Acknowledgement

S.P. is supported by the ANID FONDECYT postdoctoral program no. 3240145 and an appointment to the NASA Postdoctoral Program at the NASA–Goddard Space Flight Center, administered by Oak Ridge Associated Universities under contract with NASA. V.D. acknowledges the financial contribution from PRIN MUR 2022 (code 2022YP5ACE) funded by the European Union—NextGeneration EU. This work is based on observations made with the NASA/ESA/CSA JWST. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, under NASA contract NAS 5-03127 for JWST. These observations are associated with program JWST-GO-02044. Support for program JWST-GO-02044 was provided by NASA through a grant from the Space Telescope Science Institute.

Data Availability

The data used in this paper are associated with the JWST program GO 2044 and are available from the Mikulski Archive for Space Telescopes (https://mast.stsci.edu). The dataset is available at https://doi.org/10.17909/a2vk-mh23. The data used for host star measurements are associated with the UVES/VLT Program (106.20ZM.00) and the XShooter/VLT Program (103.2008.001) and are available from the ESO Archive (https://archive.eso.org/).

Code Availability

This study made use of the following software codes to analyse the data: NumPy⁸⁴, astropy⁸⁵, matplotlib⁸⁶, SciPy⁸⁷, pandas⁸⁸, ForMoSA^20,21, VIRGA^69,70, PICASO^71,72, pyMultinest⁴¹, WebbPSF³⁸ and petitRADTRANS²³. The spectral extraction script used for the MIRI LRS data is available at GitHub (https://github.com/mperrin/miri_lrs_fm).