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Dynamic studies to estimate the shape from Chariklo.

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Taís Alves SIlva Ribeiro
Total Authors: 1
Document type: Master's Dissertation
Press: Guaratinguetá. 2018-10-05.
Institution: Universidade Estadual Paulista (Unesp). Faculdade de Engenharia. Guaratinguetá
Defense date:
Advisor: Othon Cabo Winter

Chariklo’s stellar occultations in 2013 revealed something that was unknown to date: particle rings around a celestial body of the Solar system other than a planet. This fact has aroused the interest of the scientific community on issues such as the process of forming these rings, how long they will exist, how likely Chariklo bodies are to have rings or how stable they are around of a small object, compared to the planets. In this work we are interested in determining Chariklo’s physical model by maintaining the current structure of the rings. We believe that this centaur is a body similar to an ellipsoid, but we do not know exactly the dimensions of its physical axes a, b, and c. The ratios between the values of these semi axes result in different values for the Chariklo flattening and ellipticity terms which can be represented by the terms J2 and C22 in its gravitational potential. In addition to determining the limits for the Chariklo form, we also want to study the effects of flattening and ellipticity on the dynamics of ring particles. For this, we did numerical simulations using an integrator that takes into account the terms related to the coefficients J2 and C22. The system we integrate is composed of Chariklo being orbited by a particle approximately the same distance as the rings, making use of the orbital osculating elements. The objective of these simulations was to reproduce the physical characteristics of the rings obtained through stellar occultations, however we can only do this reproduction using values of J2 and C22 very small, which contradicts the hypothesis of the centaur to have significant differences between their physical semi axis. For values greater than J2 and C22 the particles describe orbits with very high eccentricities, generating a large variation in the orbital radius. Therefore, we proceed to study the system making use of the geometric orbital elements found in the Borderies and Longaretti (1987), Longaretti and Borderies (1991), Borderies-Rappaport and Longaretti (1994) and Renner and Sicardy (2006). These studies show that the use of orbital osculating elements in simulations of particles orbiting bodies that are very flattened is not adequate. Therefore, we use these new elements in our simulations considering only the term J2 and the effect of high eccentricity that before happened was corrected. However, in addition to adding the term C22, an eccentricity of the orbits of the particles has again increased significantly, an effect that has occurred when using osculating elements in the simulations considering the term J2. So we did discuss about a possible way to lessen the eccentricity brought about by Chariklo’s elipticity. Finally, besides the study on the dynamics of the particles, this work has an analysis, using sections of Poincaré, of a possible resonance responsible for the stability of the rings (AU)

FAPESP's process: 16/03727-7 - Studies on the dynamics of Chariklo's rings
Grantee:Taís Alves Silva Ribeiro
Support Opportunities: Scholarships in Brazil - Master