Shubina O. Peculiarities of short-periodic and long-periodic comets based on polarimetric and spectral observations

The thesis is devoted to the study of physical properties of dust and gas components in selected comets belonging to different dynamic classes based on polarimetric, spectral, and photometric observations. The database of comet polarimetry, created in 2005, has been updated. For the first time the parameters such as Pmin, αmin, αinv, h, Pmax, and αmax of phase-angle dependencies of linear polarization were calculated for comets’ different dynamic groups based on strict samples from the database DBCP V2.0. Analysis of created polarization distribution maps of the comet C/2012 J1 (Catalina) revealed polarization homogeny over the coma. The coma of the comet 2P/Encke demonstrated a complex structure. For the well-known gassy comet 2P/Encke it was shown that the polarization degree increases significantly after correction for the gas contamination. Lists of identified molecular emissions were created based on spectral observations of comets 2P/Encke, 103P/Hartley 2, C/2004 Q2 (Machholz), and C/2009 P1 (Garradd). The gas production rates of some molecules, the relative dust productivity, and the normalized gradient of the reflective dust capability were calculated. Photometrical studies of the comet 103P/Hartley 2 confirmed a low level of its dust productivity. For the first time short-term variations of the spectral gradient of the comet C/2013 UQ4 (Catalina) were detected based on the results of monitoring photometric observations. Moreover, spectral gradient of dust reflectivity changed the sign from the negative value to the positive one.