The Ital-FLAMES survey of the Sagittarius dwarf Spheroidal galaxy. I. Chemical abundances of bright RGB stars

TL;DR

This study analyzes the chemical composition of 15 red giant stars in the Sagittarius dwarf galaxy, revealing insights into its star formation history through detailed elemental abundances.

Contribution

First detailed high-resolution spectroscopic analysis of bright RGB stars in Sagittarius dwarf galaxy providing new chemical abundance data.

Findings

Mean metallicity of [Fe/H]=-0.41 with a tail to -1.52

Slightly subsolar alpha element ratios at higher metallicities

Alpha abundances in metal-poor stars similar to Milky Way counterparts

Abstract

We present iron and $\alpha$ 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]=-0.41$\pm$0.20 with a metal poor tail extending to [Fe/H]=-1.52. The $\alpha$ element abundance ratios are slightly subsolar for metallicities higher than [Fe/H]\gtsima-1, suggesting a slow star formation rate. The [$\alpha$/Fe] of stars having [Fe/H]$<$-1 are compatible to what observed in Milky Way stars of comparable metallicity.