The nature of stars with a common origin: clues from metallicity, elemental abundances, and kinematics

Detta är en avhandling från Department of Astronomy and Theoretical Physics, Lund University

Sammanfattning: Popular Abstract in English The aim of this thesis is to search for the origins of groups stars with similar kinematics making use of their chemical information. Based on measured elemental abundances from high-resolution spectra, a modified chemical tagging method is used to identify the potential cluster members in two cases. In first case, we employ this method to search for the lost siblings of the Sun. We find that HIP 40317 is likely a solar sibling. However, it is not directly supported by our dynamical arguments. In the second case, we explore the possible origins of a new kinematically discovered stellar stream. A star cluster can be excluded as the progenitor of the KFR08 steam based on the results of our chemical tagging experiments. We conclude that the stream could have a dynamical origin due to a strong perturbation from a massive merger event in the early epoch of the formation of the Milky Way. We are also interested in one globular cluster: NGC 6528. It is the most metal-rich globular cluster in the Galactic bugle. We derive accurate physical parameters (effective temperature, surface gravity, and metallicity) and elemental abundances for a larger group of red giant branch stars. This study shows that NGC 6528 has solar metallicity. Elemental abundance analysis of NGC 6528 members suggest that the cluster was enriched by Type II supernovae in short period. There are small contributions from the yields of both Type Ia supernovae and intermediate-mass asymptotic giant branch stars.