Gaftonyuk N. The rotational periods and binarity of selected asteroids

The thesis is devoted to determination of rotational periods of asteroids and to detection of binary asteroids by photometric observations. The work is based on CCD-observations carried out using 1-m telescope of Crimean Astrophysical Observatory in Simeiz. CCD-observations of asteroids have been initiated in 1996 in frame of European program "Asteroid hazard" in 1996. That is why near-Earth asteroids (NEAs) were the main purpose of observations. Special emphasis was pointed on recently discovered NEAs. Astrometric positions were determined for observed NEAs. Observations of main belt asteroids (MBAs) have been also made for a study of brightness opposition effect and for a comparative analysis of rotation properties of NEAs and small (D<10 km) MBAs features. Totally 32 asteroids were observed (among them 23 - NEA, 8 - MBA and 1 - Mars-crosser) during 82 nights. The rotation periods of 12 NEAs (including 6 recently discovered) and 5 MBAs were determined for the first time. The four NEAs were observed in a wide range of phase and aspect angles allowed constraining computer models of these bodies. The magnitude-phase dependencies of asteroid 5 Astraea and 444 Gyptis have been obtained down to very small phase angles (<1°). Analysis of the obtained lightcurves of 4 NEAs has revealed two rotation periods, which were assumed to indicate their binary nature. Binarity of two of them was confirmed by radar observations. The comparative analysis of available data of binary and single asteroids confirms consequences of the micrometeoroid model of the formation of asteroid satellites.