Kulyk I. Study of opposition effects of Jovian small inner satellites based on grounbased photometric observations

The dissertation is devoted to the investigation of opposition effects of Jovian inner satellites based on CCD-observations, which were obtained for the solar phase angle range from 8.1° to 0.3° at the wavelength of 887 nм. Obtained solar phase curves of the satellites allowed to reveal satellite opposition effects and compare their parameters. For the first time it is shown that a systematic variation of albedo values with distance from Jupiter exist: the brightness of satellites increases with the decreasing the distance to Jupiter. Analysis of the reflectance ratios of the leading and trailing hemispheres of the satellites indicates that the leading hemispheres of Thebe and Amalthea are brighter than the trailing ones, but the albedo distribution with respect to the hemispheres of Metis is uniform within the errors of the observations. For the first time it is shown that the value of albedo asymmetry varies from the satellite to the satellite with distance from Jupiter. It suggests the idea that the pollution of the trailing hemispheres of Thebe and Amalthea by sulfur ions is an important factor which reforms the satellite surfaces and may explain the change of the amount of albedo asymmetry within the system of the inner Jovian satellites. 321 intersatellite astrometric positions were obtained. The data is stored in the international data-base and is accessible to be used widely.