Search for rings around the large Trans-Neptunian Object (50000) Quaoar&#160;
2022-07-06

&amp;lt;p&amp;gt;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.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;Here, we will present the results of our search for rings around Quaoar based on the following observations:&amp;amp;#160;&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;Dates &amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160; Places of observations&amp;lt;br&amp;gt;2 September 2018&amp;amp;#160;&amp;amp;#160; Namibia&amp;lt;br&amp;gt;5 June 2019 &amp;amp;#160; &amp;amp;#160; &amp;amp;#160; &amp;amp;#160; &amp;amp;#160;&amp;amp;#160; Canary Islands&amp;lt;br&amp;gt;11 June 2020&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160;&amp;amp;#160; Australia, CHEOPS satellite&amp;lt;br&amp;gt;27 August 2021 &amp;amp;#160; &amp;amp;#160; &amp;amp;#160; Australia&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;These 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.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;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.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;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 &amp;quot;Lucky Star&amp;quot;&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;[Br13] Braga-Ribas et al., ApJ 773, 26 (2013)&amp;lt;br&amp;gt;[Fr10] Fraser and Brown, ApJ, 714, 1547 (2010)&amp;lt;br&amp;gt;[Le17] Leiva et al., Astron. J. 154, 159 (2017)&amp;lt;br&amp;gt;[Or17] Ortiz et al., Nature 550, 219 (2017)&amp;lt;br&amp;gt;[Sa21] Salo, H. et al., European Planetary Science Congress, EPSC2021-338 (2021)&amp;lt;br&amp;gt;[Si19] Sicardy, B. et al., Nature Astronomy 3, 146 (2019)&amp;lt;br&amp;gt;[Si21] Sicardy, B. et al., European Planetary Science Congress, EPSC2021-91 (2021)&amp;lt;/p&amp;gt;