V. Zh. Adibekyan, E. Delgado Mena, P. Figueira, S. G. Sousa, N. C. Santos, J. I. González Hernández, I. Minchev, J. P. Faria, G. Israelian, G. Harutyunyan, L. Suárez-Andrés, A. A. Hakobyan

Abstract
Context. During the past decade, several studies reported a correlation between chemical abundances of stars and condensation temperature (also known as T_c trend). However, the real astrophysical nature of this correlation is still debated.
Aims: The main goal of this work is to explore the possible dependence of the T_c trend on stellar Galactocentric distances, R_mean.
Methods: We used high-quality spectra of about 40 stars observed with the HARPS and UVES spectrographs to derive precise stellar parameters, chemical abundances, and stellar ages. A differential line-by-line analysis was applied to achieve the highest possible precision in the chemical abundances.
Results: We confirm previous results that [X/Fe] abundance ratios depend on stellar age and that for a given age, some elements also show a dependence on R_mean. When using the whole sample of stars, we observe a weak hint that the T_c trend depends on R_mean. The observed dependence is very complex and disappears when only stars with similar ages are considered.
Conclusions: To conclude on the possible dependence of the T_ctrend on the formation place of stars, a larger sample of stars with very similar atmospheric parameters and stellar ages observed at different Galactocentric distances is needed.

Keywords
techniques: spectroscopic, stars: abundances, stars: atmospheres, Galaxy: disk, Galaxy: evolution

Notes
Based on observations collected with the HARPS spectrograph at the 3.6-m telescope (program ID: 095.D-0717(A)), installed at the La Silla Observatory, ESO (Chile), with the UVES spectrograph at the 8-m Very Large Telescope (program ID: 095.D-0717(B)), installed at the Cerro Paranal Observatory, ESO (Chile). Also based on data obtained from the ESO Science Archive Facility under request numbers: vadibekyan180760, vadibekyan180762, vadibekyan180764, vadibekyan180768, vadibekyan180769, vadibekyan180771, vadibekyan180773, vadibekyan180778, and vadibekyan180779.

Tables with stellar parameters and chemical abundances are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/592/A87

Astronomy & Astrophysics
Volume 592, Article Number A87, Number of pages 12
2016 August

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