Obtenção dos parâmetros rotacionais e escala de troianos de Júpiter através de curvas de rotação e ocultações

Abstract

The study of the small bodies located at the L4 and L5 Lagrange points of the planet Jupiter can provide important information about the early Solar System and the dynamic evolution of this gas giant. The shape and rotational parameters of these objects, known as Jupiter Trojans, can reveal characteristics about their region of formation and their collisional past. In order to obtain more information about these bodies, located approximately 5 astronomical units from Earth, this work gathers new rotation light curves and stellar occultations data for the Trojans (624) Hektor, (3451) Mentor and (911) Agamemnon. Using computational methods such as parallel processing and genetic algorithms, the new data was confronted with convex three-dimensional models provided in the literature by the Database of Asteroid Models from Inversion Techniques (DAMIT). Synthetic rotation light curves were generated using the three-dimensional models and compared with the observed curves using the Root Mean Squared Deviation (RMSD) method. Varying the rotational parameters of the 3D model during these tests indicated which poles (𝜆, 𝛽), rotational periods (𝑃), and initial phase angles (𝜑0) best fit the data. The best values found were tested on the stellar occultation data using the 𝜒2 method, obtaining the results that fits both techniques simultaneously. This methodology allowed us to obtain the rotational parameters of these Trojans and their dimension, making it possible to determine their geometric albedo. For the Trojan (911) Agamemnon, a new three-dimensional shape was also derived using the light curve inversion software All-Data Asteroid Modeling (ADAM). The results obtained for Agamemnon’s new model indicate that non-convex shapes are more adequate for representing these objects. In addition, two double chords observed during occultations by Hektor and Mentor show that simple ellipsoids cannot explain their shape, indicating large topographic features.