Sulfur abundances in the Galactic bulge and disk

Context. The measurement of α-element abundances provides a powerful tool for placing constraints on the chemical evolution and star formation history of galaxies. The majority of studies on the α-element sulfur (S) are focused on local stars, making S behavior in other environments an astronomical topic that is yet to be explored in detail. 

Aims. The investigation of S in the Galactic bulge was recently considered for the first time. This work aims to improve our knowledge on S behavior in this component of the Milky Way.

Methods. We present the S abundances of 74 dwarf and sub-giant stars in the Galactic bulge, along with 21 and 30 F and G thick- and thin-disk stars, respectively. We performed a local thermodynamic equilibrium analysis and applied corrections for non-LTE on high resolution and high signal-to-noise UVES spectra. S abundances were derived from multiplets 1, 6, and 8 in the metallicity range of −2 < [Fe/H] < 0.6, by spectrosynthesis or line equivalent widths. 

Results. We confirm that the behavior of S resembles that of an α-element within the Galactic bulge. In the [S/Fe] versus [Fe/H] diagram, S presents a plateau at low metallicity, followed by a decreasing of [S/Fe] with the increasing of [Fe/H],  before reaching [S/Fe] ∼ 0 at a super-solar metallicity. We found that the Galactic bulge is S-rich with respect to both the thick- and thin-disks at −1 < [Fe/H] < 0.3, supporting a scenario of more rapid formation and chemical evolution in the Galactic bulge than in the disk.