Browsing by Subject "(3200) Phaethon"

The thesis discusses the observations of linear polarization occurring on the surface of near-Sun asteroid (NSA) (3200) Phaethon. As part of the research, new observational data from the Nordic Optical Telescope (NOT) are analyzed. The data were obtained in 2019, a few weeks after the perihelion passage. The scientific goal of these observations was to explain the partially conflicting results of linear polarization in earlier literature. The conflicting degrees of linear polarization in large phase angles (the Sun - the object - the observer) covered different hemispheres of Phaethon, which may be explained by the differences in surface regolith size distribution. A new pipeline was created to analyze the data. The pipeline was used to calculate the Stokes parameters of Phaethon based on the fluxes in the data frames obtained by using the ALFOSC (Alhambra Faint Object Spectrograph and Camera). The pipeline is directly applicable to other optical linear polarization data observed using ALFOSC. However, it is also applicable to sidereal observations or non-sidereal observations conducted with other instruments with relatively minor modifications. Features of the pipeline include the estimation of the uncertainty and validity of the observations by classical error propagation, as well as the possible dependence of the results based on the diameter of the circular aperture. The results of the analysis are compared to the prior observations of Phaethon presented in the literature. First, the variation of linear polarization is modeled as a function of phase angle using the Lumme-Muinonen Function (LMF) with different initial conditions. The analysis results are in line with previous results, although the data points in large phase angles have relatively large uncertainty estimates. Second, the existence of latitudinal correlation is evaluated, as such analysis is enabled by the sufficiently large total number of observations and a pole solution presented in earlier literature. No clear evidence of latitudinal correlation was found. Third, the sufficiently stable sub-observer latitude during the NOT observations allows the search for a correlation between linear polarization and rotational phase. There are consistent variation features as a function of the rotational phase, but they are classified as hints of detection in terms of statistical uncertainties (<5σ). In addition to analyzing the variation of linear polarization, a statistical summary of the orbital parameters of near-Sun asteroids is presented. To complete the thesis, a credibility analysis of all the reported results is performed.