We have determined detailed elemental abundances and stellar ages for a sample of now 38 microlensed dwarf and subgiant stars in the Galactic bulge. Stars with sub-solar metallicities are all old and have enhanced alpha-element abundances -- very similar to what is seen for local thick disk stars. The metal-rich stars on the other hand show a wide variety of stellar ages, ranging from 3-4 Gyr to 12 Gyr, and an average around 7-8 Gyr. The existence of young and metal-rich stars are in conflict with recent photometric studies of the bulge which claim that the bulge only contains old stars.
@article{arxiv.1201.2013,
title = {Signatures of an intermediate-age metal-rich bulge population},
author = {T. Bensby and S. Feltzing and A. Gould and J. A. Johnson and M. Asplund and D. Adén and J. Meléndez and J. G. Cohen and I. Thompson and S. Lucatello and A. Gal-Yam},
journal= {arXiv preprint arXiv:1201.2013},
year = {2012}
}
Comments
Poster contribution at Galactic archeology, near-field cosmology and the formation of the Milky Way, Shuzenji, Japan, 1-4 November 2011, to be published in ASP Conference Series