ИСТИНА

The interest in studying small bodies, such as asteroids and comets from different dynamic groups, as well as planetary satellites, is due to their important role in the formation and evolution of the Solar System and the origin of life on Earth. Formally, planetary satellites are not classified as small bodies, but they have common mechanisms for the occurrence of polarization of scattered radiation. The polarimetric method provides all characteristics of scattered radiation, both scalar and vector. Polarimetry is highly sensitive to the size and structure of particles and the porosity of the scattering medium, thus significantly complementing other research methods. We present the results of new polarimetric observations of near-Earth asteroids (NEAs), large satellites of Jupiter and Saturn, and both long- and short-period comets. These observations were conducted using identical two-channel photoelectric polarimeters with the 2.6 m telescope of the Crimean Astrophysical Observatory and the 2 m telescope at the Peak Terskol Observatory from 2019 to 2024. The following results were obtained and will be discussed: 1. The phase-angle dependence of polarization for 19 NEAs, including the rare high-albedo E-type asteroid 2010 XC15 with low polarization, and the low-albedo C-type asteroid 25330 (1999 KV4) with extremely high polarization. We determined the geometric albedo and sizes of some NEAs. 2. The precise shape of the negative branch of polarization for Jupiter’s moons Europa, Io, and Ganymede, as well as Saturn’s moons Dione, Rhea, and Enceladus, was established. The longitude variations of polarization for some planetary satellites were detected. Notably, temporal changes in Io's longitude polarization suggest long-term changes in the satellite's local or global volcanic activity. 3. The phase-angle dependence of polarization for 18 short-period and 25 long-period comets were obtained. Using all available data, small but systematic differences in polarization of long-period and short-period comets were found.