Spatially resolved imaging of the inner Fomalhaut disk using JWST/MIRI
Planetary debris disks around other stars are analogous to the asteroid and Kuiper belts in the Solar System. Their structure reveals the configuration of small bodies and provides hints for the presence of planets. The nearby star Fomalhaut hosts one of the most prominent debris disks, resolved by the Hubble Space Telescope, Spitzer, Herschel and the Atacama Large Millimeter Array. Images of this system at mid-infrared wavelengths using JWST/MIRI not only show the narrow Kuiper belt-analogue outer ring, but also that (1) what was thought from indirect evidence to be an asteroid-analogue structure is instead broad, extending outward into the outer system, and (2) there is an intermediate belt, probably shepherded by an unseen planet. The newly discovered belt is demarcated by an inner gap, located at ~78 au, and it is misaligned relative to the outer belt. The previously known collisionally generated dust cloud, Fomalhaut b, could have originated from this belt, suggesting increased dynamical stirring and collision rates there. We also discovered a large dust cloud within the outer ring, possible evidence of another dust-creating collision. Taken together with previous observations, Fomalhaut appears to be the site of a complex and possibly dynamically active planetary system.
© The Author(s), under exclusive licence to Springer Nature Limited 2023. We acknowledge the assistance of our programme coordinators, C. Mannfolk and B. Porterfield, especially in ensuring a quick repeat of the initially failed PSF reference observations. We thank M. Perrin and M. Lallo for updating us on the primary mirror alignment while we waited for the repeat of the PSF observations. Financial support for this work was provided by grants 80NSSC22K1293 and HST-GO-15905.001-A to the University of Arizona and also grant 80NM0018D0004 to the Jet Propulsion Laboratory, California Institute of Technology. This work is based in part on observations made with the NASA/ESA/CSA JW and HST. 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, Inc., under NASA contract NAS 5-03127 for JWST. Contributions. The observations were designed by A.G. and G.H.R. and the data were reduced and processed by A.G. and S.G.W., while all coauthors contributed to the data analysis and writing of the manuscript. Data availability. The final reduced and processed JWST MIRI imaging data that we present in this paper (and others including geometric distortion corrections) can be downloaded from https://github.com/merope82/Fomalhaut. The raw and general pipeline processed data products will be available from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute following their public release. The JWST observations are associated with programme 1193, while the HST observations are associated with programme 15905. The authors declare no competing interests.