Stability of Neptune's ring arcs in question

Abstract

Although all four of the gas-giant planets in the Solar System have ring systems, only Neptune exhibits ‘ring arcs’—stable clumps of dust that are discontinuous from each other1. Two basic mechanisms for confining the dust to these arcs have been proposed. The first2relies on orbital resonances with two shepherding satellites, while the second3 invokes a single satellite (later suggested to be Galatea4) to produce the observed ring arc structures. Here we report observations of the ring arcs and Galatea, which show that there isa mismatch between the locations of the arcs and the site of Galatea's co-rotation inclined resonance. This result calls into question Galatea's sole role in confining the arcs.