| Abstract [eng] |
This doctoral dissertation investigates the chemical composition of planet-hosting stars to better understand the connection between stellar abundances and planetary properties. The study is based on a homogeneous high-resolution spectroscopic analysis of bright F-, G-, and K-type stars with confirmed exoplanets in the Northern Hemisphere. The spectra were obtained using the Vilnius University Echelle Spectrograph mounted on 1.65 m telescope at the Molėtai Astronomical Observatory. The data were used to derive precise stellar atmospheric parameters and elemental abundances. The study focuses on light and α-elements (e.g., C, N, O, Mg, and Si) as well as neutron‑capture elements (e.g., Sr, Y, Zr, Ba, La, Ce, Pr, Nd, and Eu). Abundance ratios such as C/O, N/O, and Mg/Si were examined because of their relevance to protoplanetary disk chemistry, planetary mineralogy, and the possible composition of exoplanets. A carefully selected comparison sample of stars without detected planets was used to assess whether planet-hosting stars show distinct chemical signatures. Stellar kinematics and ages were also incorporated into the analysis. The results show that many abundance trends in planet-hosting stars are strongly influenced by Galactic chemical evolution, but several subtle differences potentially related to planet formation are identified. Planet-hosting stars show enhanced Mg and Si abundances in certain metallicity regimes, while Mg/Si ratios are lower and statistically distinct in high-mass planet systems. Neutron-capture elements generally follow Galactic chemical evolution trends, although some elements show overabundances in host stars and correlations with planet mass, particularly among giant host stars. Differential abundance trends with condensation temperature indicate enrichment in refractory elements relative to comparison stars, suggesting possible chemical imprints of planet formation. Overall, this dissertation advances our understanding of the chemical link between stars and their planets and provides observational constraints essential for refining models of exoplanet formation and internal composition. |
