Taxonomic classification of 80 near-Earth asteroids

Near-Earth objects are important not only in studying the early formation of the Solar System, but also because they pose a serious hazard to humanity when they make close approaches to the Earth. Study of their physical properties can provide useful information on their origin, evolution, and hazard to human beings. However, it remains challenging to investigate small, newly discovered, near-Earth objects because of our limited observational window. This investigation seeks to determine the visible colors of near-Earth asteroids (NEAs) , perform an initial taxonomic classification based on visible colors and analyze possible correlations between the distribution of taxonomic classification and asteroid size or orbital parameters. Observations were performed in the broadband BVRI Johnson−Cousins photometric system, applied to images from the Yaoan High Precision Telescope and the 1.88 m telescope at the Kottamia Astronomical Observatory. We present new photometric observations of 84 near-Earth asteroids, and classify 80 of them taxonomically, based on their photometric colors. We find that nearly half (46.3%) of the objects in our sample can be classified as S-complex, 26.3% as C-complex, 6% as D-complex, and 15.0% as X-complex; the remaining belong to the A- or V-types. Additionally, we identify three P-type NEAs in our sample, according to the Tholen scheme. The fractional abundances of the C/X-complex members with absolute magnitude H ≥ 17.0 were more than twice as large as those with H < 17.0. However, the fractions of C- and S-complex members with diameters ≤1 km and >1 km are nearly equal, while X-complex members tend to have sub-kilometer diameters. In our sample, the C/D-complex objects are predominant among those with a Jovian Tisserand parameter of T_J < 3.1. These bodies could have a cometary origin. C- and S-complex members account for a considerable proportion of the asteroids that are potentially hazardous.