Photometry studies of physical properties for Near-Earth asteroids

Near-Earth asteroids (NEAs), orbiting around the sun in the proximal space of the Earth, and they have become crucial for two reasons. Some of them, identified as potentially hazardous asteroids, pose the danger of collision with the Earth. They are adopted as the targets for investigating the origin of the planets and small bodies of the solar system, and for sampling and mining in future space missions. However, we couldnot "see" them in detail directly, even with the aid of the largest ground-based telescopes, owing to their small size. Hence, it is difficult to determine the size and shape of NEAs and more challenge to determine their mass and internal structure. Currently, some inversion techniques are applied to determine the basic physical properties (spin parameters, size, shape, scattering parameters, and composition) of asteroids. Among these techniques, the photometry inversion method is widespread used, by which the spin parameters, shape, and scattering parameters of asteroids are subtracted from the photometric data of asteroids. Assuming cartain an experimental scattering law and certain a shape model a series of brightness models of asteroids, and the models were used to inverse the spin parameters, shape, and scattering parameters of asteroids using the least-square and/or Markov chain Monte Carlo approaches. We used the Lommel-Seeliger ellipsoid model to estimate the physical parameters of the near-Earth asteroid (155140) 2005 UD based on its photometric data. Further, the photometric data of (106) Dione were analyzed using the Cellinoid shape model. Based on the convex shape model, we analyzed the photometric data of (103) Hera and (346) Hermentaria. Furthermore, a hierarchical analysis platform was built to determine the basic physical parameters of near-Earth asteroids efficiently, which contained a series of brightness models developed based on an assumed scattering law and a selected shape model. For the targets with sufficient data (photometric data obtained for at least four apparitions), the best values of the parameters involved in the convex inversion and their uncertainties can be estimated using a Monte Carlo simulation procedure. © 2020, Science Press. All right reserved.