DE ESTRELAS DO CAMPO A AGLOMERADOS ABERTOS: ESTUDOS QUÍMICOS BASEADOS EM ESPECTROS DE ALTA RESOLUÇÃO

Abstract

FROM FIELD STARS TO OPEN CLUSTERS: CHEMICAL STUDIES BASED ON HIGH-RESOLUTION SPECTRA Abstract This work presents four comprehensive chemical studies about red giant stars belonging to the field and two open clusters. The targets are the giants HD 150382 and TYC 8327-1678-1, which are classified as lithium-rich giant stars, and the red giant populations of the young open clusters NGC 2345 and NGC 6124. The standard spectroscopic analysis method was adopted and our results are based on high-resolution spectrum, R≈48000. When studying open clusters, we determined abundances for 20 chemical species and found the projected rotational velocity (v sin i), which in some cases can affect the abundance of some deep/extra mixing tracers. On the other hand, when we study the Li-rich giant stars, we seek to test alternative models and provide observational constraints to improve these models, since the enrichment of lithium in red giants continues as a puzzle for stellar astrophysics. Age, mass, distance, among others, are obtained and a punctual discussion where eventual peculiarities, chemical or cinematic, is presented. As part of the results, we did not find a single hypothesis that explained the lithium enrichment in our targets - we defend the hypotheses of cool bottom processing and merger between a He white dwarf and a red giant star. We verified the low average iron abundance for NGC 2345, given its galactocentric distance, and an uncommon incidence of anomalous and rapid rotators composing the population of red giants of NGC 6124.