Kreiseltheoretische Kartierung kometarer Gyrationen

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The dissertation investigates the causes of short-term, i.e. typically occurring on the order of days, brightness fluctuations in comets. Based on an inventory of the currently known phenomenology of cometary phenomena, essential parameters for describing the structure and dynamics of the comet nucleus are summarized within an analytically describable model concept. Thus, the short-term variation of cometary brightness is attributed to the quasi-periodic movement (gyration) of an asymmetric comet nucleus, which is conceived as a force-free gyroscope. Through the complex rotation of the comet nucleus, discrete sublimation areas on the comet surface are quasi-periodically exposed to incident solar radiation. This leads to a time-delayed variation of brightness within the cometary coma, which can be determined photometrically. The dependence of the comet nucleus dynamics on all essential model parameters is completely mapped for the first time through the introduction of homologous gyration classes. The thereby accessible catalog of analytically calculated light curves can be used for identification of observed light curves and for quantification of the associated cometary state variables (comet nucleus geometry, gyration state, position and number of sublimation areas) can be used. As an example, the classification is performed on observations of Halley's Comet (in the period 29.03.-18.04.1986) and critically discussed in relation to all comparable studies.