Korsun P. Physical properties of the distant comets according to the observation data and numerical modeling

The work is devoted to study of physical and dynamical characteristics of particles in dust comae and tails and gas environment in comets at large distances from the Sun. A long-term program to study distant comets "The physical properties of comets that exhibit activity at significant heliocentric distances" was initiated and implemented at the 6-m BTA telescope (SAO RAS). For the first time, as a result of the analysis of the spectra of comet C/2002 VQ94 (LINEAR), the emission bands CO+ and N2+ were recorded at record distances from the Sun, 8.36 AU. The observations of the N2+ bands are recognized as the only ones in the history of terrestrial observations of comets, which are comprehensively grounded. For the first time, in the spectra of comets a number of emission lines belonging to the C2 molecule, which arise as a result of transitions from high rotational energy levels, are identified. For the first time, an original model for the cometary dust tail formation, based on the Monte Carlo statistical algorithm, was developed. From other available codes it is advantageously distinguished by taking into account the sublimation of the ice component of the dust particles. Modeling of the dust formation of the comets showed the need of taking into account the outflow of matter from local sources on the surfaces of the nuclei whose rotation axis can have a significant inclination to the orbital plane. The model runs showed that the typical size of the dust particles is 5–1000 mkm, the size distribution can be fitted by the power law of а−3...а−4.5, the outflow velocities of dust vary from centimeters to meters per second. The effectiveness of a new mechanism for the formation of the striated features in the dust tails of the comets of the comets has been proposed and confirmed by numerical modeling.