Ponomarenko V. Spectral peculiarities selected Jupiter-family comets and long-period comets with retrograde motion.

The dissertation is devoted to research of the physical characteristics of selected comets that belong to two dynamic groups: Jupiter-family comets (JFCs) and long-period comets (LPC) with retrograde motion. The investigation was carried out on the basis of the optical spectra with an average resolution. As the result of the work a list of emission lines was created from the spectra of comets 81P/Wild 2, 103P/Hartley 2, C/2007 N3 (Lulin), C/2009 K5 (McNaught). At a considerable distance from the Sun (r > 1.5 A.U.) doublet Na (D1 = 588.9 nm, D2 = 589.6 nm) was identified in the spectra of comets. It was found that for equal heliocentric distances a quantity emission lines in the investigated LPC above their quantity in JFCs. For the first time the luminescent continuum in the perinuclear region was detected in comets 81P/Wild 2, 103P/Hartley 2, C/2007 N3 (Lulin), C/2009 K5 (McNaught). The parameters of the continuum were researched. The fluorescence is proposed as the most probable mechanism for the formation of the continuum. Complex organic substances-luminophors which are the sources of the continuum were considered. The luminescence was detected in three segments of the visible spectral range with the maxima 400.0 nm, 585.0 nm, 650.0 nm. The spectrophotometric gradient (change in reflectivity) and the relative productivity of dust were found for all investigated comets. The values of the physical parameters of the neutral gas atmospheres were obtained for comets 81P/Wild 2, 103P/Hartley 2, C/2007 N3 (Lulin), C/2009 K5 (McNaught), C/2009 P1 (Garradd): fluxes, the quantity of molecules, the gas productivity and characteristic scales for main parent and daughter molecules. It is noted that the gas and dust productivity of discussed LPC is higher their productivity in JFCs (taking into account the heliocentric distance).