Search for rings around the large Trans-Neptunian Object (50000) Quaoar

The Trans-Neptunian Object (50000) Quaoar, classified as a cubewano, is a dwarf planet candidate with a diameter of 1110 km [Br13], semi-major axis of 43.7 au and orbital eccentricity of 0.04. Its satellite Weywot orbits at 13,300 km from the primary object, and from its flux [Fr10], its diameter is about 90 km, assuming the same albedo as Quaoar. Several campaigns were conducted under the umbrella of the Lucky Star project (https://lesia.obspm.fr/lucky-star/) to observe stellar occultations by Quaoar and Weywot. Besides measuring Quaoar's and Weywot's size and shapes, those campaigns aimed at searching for material around Quaoar.Here, we will present the results of our search for rings around Quaoar based on the following observations: Dates Places of observations2 September 2018 Namibia5 June 2019 Canary Islands11 June 2020 Australia, CHEOPS satellite27 August 2021 AustraliaThese campaigns were undertaken in a context where rings are already known to exists around other small bodies of the solar system: the Centaur object Chariklo [Br14] and the dwarf planet Haumea [Or17]. These two ring systems, in spite of large differences in sizes and heliocentric distances, both orbit close to the 1/3 Spin-Orbit Resonance (SOR) with the central body [Or17,Le17], meaning that the latter completes three rotations while a ring particle completes one orbital revolution. Because of their non-axisymmetric shapes, and contrarily to giant planets, Chariklo and Haumea induce strong SORs [Si19]. Theoretical calculations [Si21] and numerical simulations of collisional disks [Sa21] show that the 1/3 SOR is indeed a possible cause of confinement of a narrow ring.If ring exists at the Quaoar 1/3 SOR, it should be close to an orbital radius of 4,200 km. This represents 7.5 Quaoar's radii, well outside the Roche limit of the central body. So, if a dense ring were to be confined near this resonance, it is expected to accrete into a satellite, and thus disappear over a short time scale. We will discuss models that could maintain a colliding disk near the Quaoar 1/3 SOR in spite of this obstacle.Acknowledgments. The work leading to these results has received funding from the European Research Council under the European Community's H2020 2014-2021 ERC Grant Agreement no. 669416 "Lucky Star"[Br13] Braga-Ribas et al., ApJ 773, 26 (2013)[Fr10] Fraser and Brown, ApJ, 714, 1547 (2010)[Le17] Leiva et al., Astron. J. 154, 159 (2017)[Or17] Ortiz et al., Nature 550, 219 (2017)[Sa21] Salo, H. et al., European Planetary Science Congress, EPSC2021-338 (2021)[Si19] Sicardy, B. et al., Nature Astronomy 3, 146 (2019)[Si21] Sicardy, B. et al., European Planetary Science Congress, EPSC2021-91 (2021)