A dense ring around the TNO Quaoar outside its Roche Limit

Prof. Altair Gomes, Physics Institute, Universidade Federal de Uberlândia. April 6th, 2023

The Trans-Neptunian Object (50000) Quaoar, classified as a cubewano, is a dwarf planet candidate with a diameter of 1,110 km, a semi-major axis of 43.7 au, and an orbital eccentricity of 0.04. Its satellite Weywot orbits at 13,300 km from the primary object, and its diameter is about 90 km, derived from its flux, assuming the same albedo as Quaoar. It allows the determination of Quaoar's mass. Over the years, several campaigns were conducted within the ERC Lucky Star project to observe stellar occultations by Quaoar and Weywot. Besides measuring Quaoar's and Weywot's sizes and shapes, those campaigns aimed at searching for material around this TNO. The events analyzed in this work were observed between 2018 and 2021, and in these high-quality occultation light curves, besides the main body occultation, secondary events were also observed, and they could be explained as a dense ring surrounding Quaoar at about 4,100 km (7.4 Quaoar radii). One important detail is that this region is well outside the Roche limit of the central body of 1,780 km (3.2 Quaoar radii), assuming that the bulk density of particles would be around 400 kg m-3 (typical of Saturnian small satellites). This discovery will be discussed in detail during the presentation.

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Download slides of the talk here: https://drive.google.com/file/d/1HoDw...