Dynamical Implications of the Recently Detected Feature around Quaoar and Constraints on the Presence of Additional Satellites

A recently reported opaque feature in the Quaoar system, detected during the 2025 June 25 stellar occultation, has been interpreted as either an ∼15 km radius satellite or a dense, sharp-edged arc orbiting at about 5600–5900 km. Here, we investigate both scenarios through numerical integrations that include Quaoar, its triaxial shape, and Weywot. If the feature is a satellite, stability maps show that it acquires a forced eccentricity of about 0.002 and has only a minor dynamical effect on the Q1R and Q2R rings. Its main effect is to clear a narrow region around its orbit, associated with the overlap of mean motion resonances, preventing the long-term survival of kilometer-scale moons within ∼1 Quaoar radius of the satellite. If instead the feature is an arc, we test confinement around the triangular equilibrium point of an unseen co-orbital satellite. While azimuthal confinement is readily obtained for satellites with satellite-to-primary mass ratios up to 10 −3 , Weywot’s secular perturbation induces large radial excursions in the arc particles, preventing reproduction of the observed radial extent. The required radial confinement is achieved only for confiners comparable to or more massive than Weywot, which would likely be detectable by direct imaging. We therefore disfavor triangular-point confinement as an explanation for a long-lived dense arc and argue that the feature is more dynamically consistent with a satellite. We identify broad stable zones where additional undetected moons could reside, including near the rings as possible shepherd moons. Furthermore, Quaoar’s ellipticity alone is sufficient to induce nonresonant orbital excitation capable of preventing ring coagulation, an effect that may be enhanced by small moons near the rings.