Volume 541, May 2012
|Number of page(s)||9|
|Section||Galactic structure, stellar clusters and populations|
|Published online||22 May 2012|
Stellar substructures in the solar neighbourhood
I. Kinematic group 3 in the Geneva-Copenhagen survey⋆
Institute of Theoretical Physics and Astronomy (ITPA), Vilnius
A. Gostauto 12,
e-mail: email@example.com; firstname.lastname@example.org; email@example.com
2 Niels Bohr Institute, Copenhagen University, Juliane Maries Vej 30, 2100 Copenhagen, Denmark
Received: 29 December 2011
Accepted: 8 March 2012
Context. Galactic archeology is a powerful tool for investigating the formation and evolution of the Milky Way. We use this technique to study kinematic groups of F- and G-stars in the solar neighbourhood. From correlations between orbital parameters, three new coherent groups of stars were recently identified and suggested to correspond to remnants of disrupted satellites.
Aims. We determine detailed elemental abundances in stars belonging to one of these groups and compare their chemical composition with Galactic disc stars. The aim is to look for possible chemical signatures that might give information about the history of this kinematic group of stars.
Methods. High-resolution spectra were obtained with the FIES spectrograph at the Nordic Optical Telescope, La Palma, and analysed with a differential model atmosphere method. Comparison stars were observed and analysed with the same method.
Results. The average value of [Fe/H] for the 20 stars investigated in this study is −0.69 ± 0.05 dex. Elemental abundances of oxygen and α-elements are overabundant in comparison with Galactic thin-disc dwarfs and thin-disc chemical evolution models. This abundance pattern has similar characteristics as the Galactic thick-disc.
Conclusions. The homogeneous chemical composition together with the kinematic properties and ages of stars in the investigated Group 3 of the Geneva-Copenhagen survey provides evidence of their common origin and possible relation to an ancient merging event. The similar chemical composition of stars in the investigated group and the thick-disc stars might suggest that their formation histories are linked.
Key words: stars: abundances / Galaxy: evolution / Galaxy: disk / Galaxy: formation
Table 3 is available in electronic form at http://www.aanda.org
© ESO, 2012
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.