Zinc abundances in the Sculptor dwarf spheroidal galaxy^,⋆,⋆⋆

¹ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
e-mail: skuladottir@mpia.de
² Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands
³ Dipartimento di Fisica e Astronomia, Universita’ di Firenze, via G. Sansone 1, Sesto Fiorentino, Italy
⁴ INAF/Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, Firenze, Italy
⁵ GEPI, Observatoire de Paris, PSL Research University, CNRS, Place Jule Janssen, 92190 Meudon, France
⁶ Laboratoire Lagrange, Université de Nice Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, CS34229, 06304 Nice Cedex 4, France
⁷ Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK

Received: 11 May 2017
Accepted: 18 July 2017

Abstract

From ESO VLT/FLAMES/GIRAFFE spectra, abundance measurements of Zn have been made in ≈100 individual red giant branch (RGB) stars in the Sculptor dwarf spheroidal galaxy. This is the largest sample of individual Zn abundance measurements within a stellar system beyond the Milky Way. In the observed metallicity range, −2.7 ≤ [Fe/H] ≤ −0.9, the general trend of Zn abundances in Sculptor is similar to that of α-elements. That is, super-solar abundance ratios of [Zn/Fe] at low metallicities, which decrease with increasing [Fe/H], eventually reaching subsolar values. However, at the higher metallicities in Sculptor, [Fe/H] ≳ −1.8, we find a significant scatter, −0.8 ≲ [Zn/Fe] ≲ +0.4, which is not seen in any α-element. Our results are consistent with previous observations of a limited number of stars in Sculptor and in other dwarf galaxies. These results suggest that zinc has a complex nucleosynthetic origin, behaving neither completely like an α- nor an iron-peak element.