JWST Spectrophotometry of the Small Satellites of Uranus and Neptune

Abstract We use 1.4–4.6 μ m multiband photometry of the small inner Uranian and Neptunian satellites obtained with the James Webb Space Telescope’s near-infrared imager NIRCam to characterize their surface compositions. We find that the satellites of the ice giants have, to first order, similar compositions to one another, with a 3.0 μ m absorption feature possibly associated with an O-H stretch, indicative of water ice or hydrated minerals. Additionally, the spectrophotometry for the small ice-giant satellites matches spectra of some Neptune Trojans and excited Kuiper Belt objects, suggesting shared properties. Future spectroscopy of these small satellites is necessary to identify and better constrain their specific surface compositions.