2024ApJ...977..277S

We present images of the Vega planetary debris disk obtained at 15.5, 23, and 25.5 μm with the Mid-Infrared Instrument on JWST. The debris system is remarkably symmetric, smooth, and centered accurately on the star. There is a broad Kuiper-belt-analog ring at ∼80-170 au that coincides with the planetesimal belt detected with the Atacama Large Millimeter/submillimeter Array at 1.34 mm. The interior of the broad belt is filled with warm debris that shines most efficiently at mid-infrared, along with a shallow flux dip/gap at 60 au from the star. These qualitative characteristics argue against any Saturn-mass planets orbiting the star outside of about 10 au, assuming the unseen planet would be embedded in the very broad planetesimal disk from a few to hundreds of astronomical units. We find that the distribution of dust detected interior to the broad outer belt is consistent with grains being dragged inward by the Poynting-Robertson effect. Under the drag-dominated disk assumption, tighter constraints can be derived for planets in specific locations; for example, any planet shepherding the inner edge of the outer belt is likely to be less than six Earth masses. The disk surface brightness profile along with the available infrared photometry suggest a disk inner edge near ∼3-5 au, disconnected from the sub-astronomical-unit region that gives rise to the hot near-infrared excess. The gap between the hot, sub-astronomical-unit zone and the inner edge of the warm debris might be shepherded by a modest-mass, Neptune-size planet.