The Ital-FLAMES survey of the Sagittarius dwarf spheroidal galaxy

I. Chemical abundances of bright RGB stars

¹ Istituto Nazionale di Astrofisica – Osservatorio Astronomico di Trieste, via Tiepolo 11, 34131 Trieste, Italy e-mail: lmonaco@eso.org
² Istituto Nazionale di Astrofisica – Osservatorio Astronomico di Bologna, 40127 Bologna, Italy
³ Università di Bologna – Dipartimento di Astronomia, 40127 Bologna, Italy
⁴ European Southern Observatory, Casilla 19001, Santiago, Chile
⁵ Istituto Nazionale di Astrofisica – Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monteporzio Catone, Roma, Italy
⁶ Università Tor Vergata, Roma, Italy

Received: 28 April 2005
Accepted: 22 June 2005

Abstract

We present iron and α element (Mg, Ca, Ti) abundances for a sample of 15 Red Giant Branch stars belonging to the main body of the Sagittarius dwarf Spheroidal galaxy. Abundances have been obtained from spectra collected using the high resolution spectrograph FLAMES-UVES mounted at the VLT. Stars of our sample have a mean metallicity of [ Fe/H with a metal-poor tail extending to [ Fe/H. The α element abundance ratios are slightly subsolar for metallicities higher than , suggesting a slow star formation rate. The [ α/Fe] of stars having are compatible to what observed in Milky Way stars of comparable metallicity.