Stellar substructures in the solar neigbourhood. I. (Stonkute et al.)

Vol. 541
In section 5. Galactic structure, stellar clusters and populations

Stellar substructures in the solar neigbourhood. I. Kinematic group 3 in the Geneva-Copenhagen survey

by E. Stonkute, G. Tautvaisiene, B. Nordström, and R. Zenoviene, A&A 541, A157


A coherent group of stars was kinematically selected from the Geneva-Copenhagen survey of F and G stars in the solar neighbourhood. It is suggested to correspond to the remnants of a disrupted satellite galaxy. This paper reports the results of a detailed elemental abundance analysis of 20 stars in this group from the high-resolution FIES spectrograph at the Nordic Optical Telescope (La Palma). The abundances are quite homogeneous, with an average iron abundance, [Fe/H]= -0.7, and an alpha-element abundance that is higher than expected of Galactic thin disk stars, but still broadly consistent with the properties expected of the Galactic thick disk stars. The uniform properties of these 20 stars suggest a common origin, perhaps an ancient merging event, and the analysis of their abundances suggests a relation to the formation of the thick disk.