Análise de dados para caracterização de assimetrias longitudinais do anel C1R de Chariklo

Abstract

For hundreds of years, ring systems were only known to exist around the giant planets of the Solar System. However, in 2013, this view changed with the discovery of a ring system around the Centaur Chariklo. The existence of rings around small bodies in the Solar System expanded the possibilities for new studies on the formation, evolution, and characteristics of rings. In particular, longitudinal variations in the width of Chariklo’s C1R ring were identified. However, unlike what happened with the planets, there are no plans to send space probes to study these rings inloco. Therefore, the characterization of these rings must be carried out using indirect methods, such as the stellar occultation method. The methodology consists of using the Stellar Occultation Reduction and Analysis package (SORA) and data from various occultations to relate the observation reference plane to the ring’s orbital plane, determining the spatial distribution of ring points as a function of orbital longitude and calculating the coordinates in the ring reference frame for each detection, also allowing an estimation of the ring’s width. By using temporal information, it is possible to define characteristic velocities and identify oscillation modes that best describe the rings, using sinusoidal models. By fitting this model to the data using oscillation modes 1, 2, or 3 and their combinations, it was concluded that the best fit occurs with a combination of modes 1 and 2. The amplitude of the most probable oscillation modes ranges from 0.9 ± 0.2 to 0.8 ± 0.3 km, and the most probable ring width is 6.7 ± 0.2 km. When constraining the angular velocity of the oscillation mode, the solutions suggest an angular velocity of Ω1 = 3.8 ± 0.6 and Ω2 = 620.9 ± 0.4 degrees/day. Finally, after several analyses and using as many resolved observations of Chariklo as possible, relevant information about its newly discovered rings was obtained.