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

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: . We also show that this cluster displays the same low α-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.