Volume 572, December 2014
|Number of page(s)||21|
|Section||Galactic structure, stellar clusters and populations|
|Published online||04 December 2014|
The chemical composition of red giants in 47 Tucanae
Zentrum für Astronomie der Universität Heidelberg,
Landessternwarte, Königstuhl 12,
2 Millennium Institute of Astrophysics, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago, Chile
3 Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago, Chile
4 Department of Astronomy and Astronomical Observatory, Odessa National University, Isaac Newton Institute of Chile, Odessa Branch, Shevchenko Park, 65014 Odessa, Ukraine
5 GEPI, Observatoire de Paris, CNRS, Université Paris Diderot, Place Jules Janssen, 92190 Meudon, France
6 Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 0200, Australia
7 INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
8 INAF – Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monte Porzio Catone, Italy
9 Departamento de Astronomia do IAG/USP, Universidade de Saõ Paulo, rua do Mãtao 1226, 05508-900 Saõ Paulo, SP, Brasil
10 INAF – Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
Received: 4 July 2014
Accepted: 12 September 2014
Context. The study of chemical abundance patterns in globular clusters is key importance to constraining the different candidates for intracluster pollution of light elements.
Aims. We aim at deriving accurate abundances for a wide range of elements in the globular cluster 47 Tucanae (NGC 104) to add new constraints to the pollution scenarios for this particular cluster, expanding the range of previously derived element abundances.
Methods. Using tailored 1D local thermodynamic equilibrium (LTE) atmospheric models, together with a combination of equivalent width measurements, LTE, and NLTE synthesis, we derive stellar parameters and element abundances from high-resolution, high signal-to-noise spectra of 13 red giant stars near the tip of the RGB.
Results. We derive abundances of a total 27 elements (O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Mo, Ru, Ba, La, Ce, Pr, Nd, Eu, Dy). Departures from LTE were taken into account for Na, Al, and Ba. We find a mean [Fe/H] = −0.78 ± 0.07 and [ α/ Fe ] = 0.34 ± 0.03 in good agreement with previous studies. The remaining elements show good agreement with the literature, but including NLTE for Al has a significant impact on the behavior of this key element.
Conclusions. We confirm the presence of an Na-O anti-correlation in 47 Tucanae found by several other works. Our NLTE analysis of Al shifts the [Al/Fe] to lower values, indicating that this may be overestimated in earlier works. No evidence of an intrinsic variation is found in any of the remaining elements.
Key words: globular clusters: individual: 47 Tucanae / stars: abundances / stars: fundamental parameters / methods: observational / techniques: spectroscopic
Based on observations made with the ESO Very Large Telescope at Paranal Observatory, Chile (Programmes 084.B-0810 and 086.B-0237).
Full Tables 2, 5, and 9 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (22.214.171.124) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/572/A108
Appendix A is available in electronic form at http://www.aanda.org
© ESO, 2014
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