Spatially resolved imaging of the inner Fomalhaut disk using JWST/MIRI

Abstract

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. JWST mid-infrared images of the nearby star Fomalhaut reveal a complex system of dusty rings and disks, created as debris from planetesimal collisions. These structures suggest the presence of a complex and probably dynamically active planetary system.