Estimation of unknown physical properties of near-Earth asteroids for dynamical study

Abstract

A member of Near-Earth Asteroids (NEAs) has orbit (at least a part) moving across a distance within 1.3 astronomical unit from the Sun. Many of them, however, lack of physical properties that are important for studying their global dynamics. Results of long-term dynamical study of NEAs can be more significant if the Yarkovsky thermal effects are included, meaning that this needs the physical properties. To overcome this problem, here we propose a scheme to estimate unknown physical properties of NEAs, i.e. albedo, size, rotation period, pole orientation, bulk and surface densities, thermal conductivity, thermal capacity, and infrared emissivity. The scheme is started with the known absolute magnitudes and the known taxonomy classes of NEAs. Albedos are derived from the taxonomy classes, and eventually sizes can be determined. The sizes provide rotation periods and pole orientations using recent published results. Finally, by modeling some types of asteroid surfaces, the rest properties can be obtained. The scheme is used to provide the estimated physical properties of more than ten thousands NEAs representing their general picture needed for global dynamical study.