Site Map
Follow us on Facebook Follow us on Twitter YouTube channel
Centro de Astrofísica da Universidade do Porto

Search for associations containing young stars (SACY)
II. Chemical abundances of stars in 11 young Associations in the Solar neighborhood

P. Viana Almeida, N. C. Santos, C. Melo, M. Ammler-von Eiff, C. A. O. Torres, G. R. Quast, J. F. Gameiro, M. Sterzik

The recently discovered coeval, moving groups of young stellar objects in the solar neighborhood represent invaluable laboratories to study recent star formation and to search for high metallicity stars which can be included in future exo-planet surveys. In this study we derived through an uniform and homogeneous method stellar atmospheric parameters and abundances for iron, silicium and nickel in 63 post-T Tauri Stars from 11 nearby young associations. We further compare the results with two different pre-main sequence (PMS) and main sequence (MS) star populations. The stellar atmospheric parameters and the abundances presented here were derived using the equivalent width of individual lines in the stellar spectra through the excitation/ionization equilibrium of iron. Moreover, we compared the observed Balmer lines with synthetic profiles calculated for model atmospheres with a different line formation code. We found that the synthetic profiles agree reasonably well with the observed profiles, although the Balmer lines of many stars are substantially filled-in, probably by chromospheric emission. Solar metallicity is found to be a common trend on all the nearby young associations studied. The low abundance dispersion within each association strengthens the idea that the origin of these nearby young associations is related to the nearby Star Forming regions (SFR). Abundances of elements other than iron are consistent with previous results on Main Sequence stars in the solar neighborhood. The chemical characterization of the members of the newly found nearby young associations, performed in this study and intended to proceed in subsequent works, is essential for understanding and testing the context of local star formation and the evolutionary history of the galaxy.

stars: pre-main sequence – stars: abundances – open clusters and associations: general – stars: fundamental parameters – solar neighborhood

Based on observations collected with the UVES spectrograph at the VLT/UT2 8.2-m Kueyen Telescope (ESO run ID. 079.C-556(A)) at the Paranal Observatory, Chile

Astronomy and Astrophysics
Volume 501, Page 965
July 2009

>> PDF>> ADS>> DOI

Institute of Astrophysics and Space Sciences

Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

Proceed on CAUP's website|Go to IA website