Search for associations containing young stars (SACY)II. Chemical abundances of stars in 11 young associations in the solarneighborhood

摘要

The recently discovered coeval, moving groups of young stellar objects in the solar neighborhood represent invaluable laboratoriesfor studying recent star formation and searching for high metallicity stars that can be included in future exo-planet surveys. In thisstudy, we derived through an uniform and homogeneous method stellar atmospheric parameters and abundances for iron, silicium,and nickel in 63 post-T Tauri stars from 11 nearby young associations. We further compare the results with two different pre-mainsequence (PMS) and main sequence (MS) star populations. The stellar atmospheric parameters and the abundances presented herewere derived using the equivalent width of individual lines in the stellar spectra by assuming the excitation/ionization equilibriumof iron. Moreover, we compared the observed Balmer lines with synthetic profiles calculated for model atmospheres with a differentline-formation code. We found that the synthetic profiles agree reasonably well with the observed profiles, although the Balmer linesof many stars are substantially filled-in, probably by chromospheric emission. Solar metallicity is found to be a common trend inall the nearby young associations studied. The low abundance dispersion within each association strengthens the idea that the originof these nearby young associations is related to the nearby star-forming regions (SFR). Abundances of elements other than iron areconsistent with previous results for Main Sequence stars in the solar neighborhood. The chemical characterization of the membersof the newly found nearby young associations, performed in this study and intended to proceed in subsequent works, is essential tounderstanding and testing the context of local star formation and the evolutionary history of the galaxy.