Family ties: Abundances in Terzan 7, a Sgr dSph globular cluster

Free access article

Issue		A&A Volume 437, Number 3, July III 2005


Page(s)		905 - 910
Section		Galactic structure, stellar clusters and populations
DOI		http://dx.doi.org/10.1051/0004-6361:20042315

A&A 437, 905-910 (2005)
DOI: 10.1051/0004-6361:20042315

Family ties: Abundances in Terzan 7, a Sgr dSph globular cluster

L. Sbordone^{1, 2}, P. Bonifacio³, G. Marconi^{1, 4}, R. Buonanno² and S. Zaggia³

¹ ESO European Southern Observatory - Alonso de Cordova 3107 Vitacura, Santiago, Chile
² Universitá di Roma 2 "Tor Vergata" - via della Ricerca Scientifica, Rome, Italy
e-mail: sbordone@mporzio.astro.it
³ Istituto Nazionale di Astrofisica - Osservatorio Astronomico di Trieste, via Tiepolo 11, 34131 Trieste, Italy
⁴ Istituto Nazionale di Astrofisica - Osservatorio Astronomico di Roma via Frascati 33, 00040 Monte Porzio Catone, Rome, Italy

(Received 4 November 2004 / Accepted 23 February 2005 )

Abstract
We study the chemical composition of 5 giant stars in the globular cluster Terzan 7 associated with the Sagittarius dwarf spheroidal galaxy ( Sgr dSph ), based on high resolution UVES-VLT spectra. We confirm the metallicity found by previous high resolution investigations: $\rm [Fe/H]\sim -0.6$ . We also show that this cluster displays the same low $\alpha$ -element to iron ratio found in Sgr dSph field stars of similar metallicity, as well as the same low Ni/Fe ratio. These chemical signatures are characteristic of the Sgr dSph system, and appear to be shared both by the globular cluster Pal 12 , which was most likely stripped from Sgr by tidal interaction, and by Pal 5 , which may also have belonged in the past to the Sgr dSph system. Intriguingly even globular cluster Ruprecht 106 , although not associated to Sgr, displays similar characteristics.

Key words: stars: abundances -- stars: atmospheres -- Galaxy: globular clusters: individual: Terzan 7 -- galaxies: abundances -- galaxies: individual: Terzan 7 -- galaxies: evolution

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