In our efforts to characterize Quaoar’s shape and search for putative material around it, we have predicted and observed several stellar occultations by this body. Following a report from Australia of a Neptune-like ring detected during a 2021 occultation and independently suspected in 2019, we have identified secondary events in previous occultations observed between 2018 and 2020. They are consistent with a circular ring centred on the body, with two possible mirror solutions for the ring orientation. Both solutions have radii close to 4,100 km, or roughly 7.4 Quaoar radii. One solution has a ring pole that presents a large mismatch with Weywot’s orbital pole, whereas the other solution is consistent with a ring coplanar with Weywot’s orbit. This is our preferred solution, as a primordial collisional system surrounding Quaoar is expected to settle in a disc that subsequently forms both the ring and Weywot.
For correction, see: Nature 626, E2 (2024). DOI: 10.1038/s41586-024-07031-w