Velichko S. Polarimetric and photometric characteristics of the dust in the atmosphere of splitting comets.

The thesis is devoted to polarimetric and photometric invastigations of the properties of dust in the atmosphere of the comets D/1999 S4 (LINEAR), C/2001 A2 (LINEAR), 153R/Ikeya-Zhang, C/2002 T7 (LINEAR), C/2004 Q2 (Machholz), 17P/Holmes, and B and C nuclei of 73R/Schwassmann-Wachmann 3, which were performed during the period from 2000 to 2007 at the 0.7-m telescope of the Institute of Astronomy of Kharkiv Karazin National University. For the first time, the sharp increase of the continuum linear polarization were detected and the change of spectral gradient of polarization of the comet D/1999 S4 (LINEAR) just after its disintegration was marked. The polarizations of the nuclei B and C comets 73R/Schwassmann-Wachmann 3 were equal one to another despite the fact that they showed different degree of activity. In addition, the spectral gradient of polarization of the nucleus B had an atypical value. After the outburst of brightness of comet 17P/Holmes the spectral gradient of its polarization reached abnormal value. The dust production in red continuum of the comet equals to values which are known for the most dusty comets. Database of polarimetry of comets was created, and it is accessible via the Internet as a part of PLANETARY DATA SYSTEM. Our new observations and database open a possibility to compose a phase dependence of polarization in the red continuum for dusty comets and calculate more precise its parameters.