Summary of my M.S. thesis


        My M.S. thesis presents results of CCD photometry in R-band of a dynamically new comet C/2001 K5 (LINEAR), obtained at a heliocentric distance r of about 5.6 AU, after the perihelion passage. Being so distant from the Sun, this comet was extremely active (Afrho close to 2000 cm), exhibiting quite well developed dust coma and tail. During the observations, general photometric behavior of the comet with heliocentric distance was well described by the 2.5nlog(r) function with coefficient n=5. The radial profiles of the coma were found to be undulated, with mean slope of the dependence between cometary magnitude and 2.5log of aperture radius (at comet distance) equal to -0.77. The light curve of comet LINEAR exhibited short-term variability which we attributed to cyclic changes of dust emission, induced by the nucleus rotation.
        Model computations by some authors have revealed that active comets can change their spin status quite substantially even during a single orbital revolution. Thus, attempting to search for a rotation frequency, we have modified the classical PDM approach by including the spin acceleration term. Such Dynamical PDM (DPDM) method revealed the most reliable solution for the frequency f0 = 0.019048 ± 0.000013 h-1 and its first time-derivative df/dt = -9.901 ± 0.046 × 10-6 h-2 (index "zero" denotes reference to the mid time of the whole observing run), indicating a rapid spin-down of the nucleus. These parameters are equivalent to the rotation period of 52.499 ± 0.036 h and its relative increment of 0.02729 ± 0.00013. We present the most probable evolution of the rotation frequency of comet LINEAR, based on the results of periodicity analysis and a simple, almost parameter independent, dynamical model of the nucleus rotation. It is also shown that the DPDM may be an effective tool for determination of a nucleus radius, which provided us with the value of 1.53 ± 0.25 km for comet LINEAR.
        The thesis was published and is available in English as an article (Drahus & Waniak 2006, Icarus 185, 544).