Sofia Feltzing

We present the first results from several ongoing studies of the stellara bundances, ages, and chemical trends in the long-lived dwarf stars in the solar neighborhood that belong to the thin and thick galactic disk.We confirm that the trends of α-elements in the thin and thick disk are distinct, and we also find that the thick disk show the typical signature of SN Ia contribution to the chemical enrichment of the interstellar gas out of which the later generations of thick disk stars formed. From a first study of the r- and s-process elements we reportpreliminary evidence that AGB stars also have contributed to the chemical enrichment in the thick disk. Furthermore, we investigate the individual as well as the collective ages of the thick disk stars andfind evidence of an overall age-metallicity relation in the thick disk.This has, to our best knowledge, not been shown before. All this indicate that the star formation in what is today's thick disk was extended over time and, at least for the stars that are today close tothe sun, the gas which the stars formed out of was well-mixed. These findings seem to rule out scenarios where the thick disk formed in a fast dissipative collapse.