Propriedades físicas de asteroides em órbitas próximas da Terra determinadas a partir da análise de suas curvas de luz

Abstract

The population of near-Earth objects (NEOs) is one of the most interesting to be studied because, in addition to its members offering risk to Earth, they are also the smallest bodies in the Solar System whose physical properties can be determined by observations from Earth. On the other hand, it is a population that, despite the high rate of discovery, lacks a better knowledge of its physical properties which are fundamental for the models of formation and evolution as well as to define the best strategy in case a collision with the Earth is foreseen. In this work, photometric data of approximately 90 asteroids were obtained, mostly members of the NEO population, with the 1-meter telescope of the Observatório Astronômico do Sertão de Itaparica (OASI, Itacuruba-PE) of the IMPACTON project. The main of the observations was to determine the rotational period, the pole direction of rotation and the shape model of the selected objects. A Fourier series analysis was used to derive the rotational periods while the pole directions and the shape models were obtained through the application of the lightcurves inversion method. The rotation periods of 44 NEOs and 10 Main Belt asteroids were determined, with values ​​between 2 and 15 hours. For another 12 NEOs, only an estimate for the rotational period was obtained. The pole direction and shape model were obtained for 6 NEOs and one Main Belt asteroid. A detailed study of the PHA (436724) 2011 UW158 was carried out whose fast rotation, of about 36 minutes, was used to analyze its internal structure restricting the necessary cohesion force to keep it intact even with high rotation. Finally, a sample of 27 NEOs candidates to be binary systems was investigated due to a rotation of about 2 hours and a low amplitude of the lightcurve. Binary evidence was found for 12 of these objects while for another 5, already confirmed as binary, their physical properties were investigated. It is worth mentioning that this study shows that the 2017 YE5 binary possibly has a cometary origin, which confirms the existence of comets among NEOs. keywords: Near Earth asteroids; rotational properties; internal structure