| Abstract [eng] |
The objective of this study was to analyze the relationships between chemical abundances, kinematic parameters, and ages in representative dwarf and giant stars with planets in the solar vicinity. The main goals of the research were to review relevant scientific publications that discuss the connections between the aforementioned topics, measure the abundances of C, N, O, Mg, Si, S, Y and Eu. The study was aimed at exploring the relationships between the kinematic parameters, age, and chemical abundances of the stars. This involved categorizing the stars into Galactic disks and analyzing the phenomenon known as cosmic clocks and identifying differences among stars with planets of different sizes. The 49 stars with planets, which are on average located 58 parsecs away from the Sun and have an average age of 5.4 billion years, were thoroughly examined. It was noted that these stars exhibit slightly higher abundances of Mg, Si, S, and Eu compared to stars without planets. It was found that stars with low mass planets (weighing up to 16 Earth's masses) have the highest Mg/Si ratio. The mean Mg/Si ratio for these stars was determined to be 1,29, whereas the overall mean for the entire sample of stars with planets was 1,09. These findings align with previous research and suggest that these low-mass planets likely have chemical compositions similar to that of Earth. The stars were further classified into thin (28 stars) and thick (9 stars) Galactic disks based on their peculiar velocities. Remarkably, this distribution not only statistically correlated with the literature-reported [Mg/Fe] abundances and age values but also revealed some discrepancies in both parameters. This indicates that when categorizing stars into Galactic disks, it is crucial to consider both chemical and kinematic parameters, as well as age, to obtain the most accurate results. When analyzing the properties of the planets, it was observed that all low-mass (up to 16 Earth's masses) planets and all but one mid-mass (more than 16 and less than 116 Earth's masses), were found orbiting dwarf stars. This suggests that the detection of planets is influenced by technical limitations, emphasizing the importance of separately examining properties of planets around dwarf and giant stars. The study also explored the ratio of neutron-capture reaction elements to alpha elements in relation to stellar ages. The [Y/Mg] ratio, known as a cosmic clock, was employed for this analysis. Notably, a correlation between [Y/Mg] and age was observed for the thin Galactic disk and stars not assigned to any specific disk (all stars with peculiar velocity lower than threshold for thick disk). The relationship was expressed as [Y/Mg]_thin* = 0.09 - 0.05 x Age[Gyr]. This finding aligns with existing scientific literature but exact numeric values of the equation slightly differ. A larger sample of stars should be investigated to establish a more precise expression. In summary, this study provides valuable insights into the relationships between stellar kinematics, chemistry, and the presence of planets. The results align with existing literature trends and highlight the importance of considering multiple parameters for accurate characterization of stars with planets. |
