The chemical evolution of manganese in different stellar systems

¹ Dipartimento di Astronomia, Universitá di Trieste, via G.B. Tiepolo 11, 34131, Italy e-mail: cescutti@oats.inaf.it
² INAF Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, 34131, Italy
³ Núcleo de Astrofísica Teórica, Universidade Cruzeiro do Sul, R. Galvão Bueno 868, Liberdade, 01506-000, São Paulo, SP, Brazil
⁴ Observatories of the Carnegie Institution of Washington, 813 Santa Barbara St., Pasadena, CA, USA

Received: 7 July 2008
Accepted: 28 August 2008

Abstract

Aims. We model the chemical evolution of manganese relative to iron in three different stellar systems: the Solar neighbourhood, the Galactic bulge, and the Sagittarius dwarf spheroidal galaxy, and we compare our results with recent and homogeneous observational data sets.

Methods. We adopt three chemical evolution models able to reproduce the main properties of the Solar vicinity, the Galactic bulge, and the Sagittarius dwarf spheroidal. We then compare different stellar yields in order to identify the most appropriate set to match the observational data in these systems.

Results. We compute the evolution of manganese in the three systems and find that to reproduce simultaneously the measurements of [Mn/Fe] versus [Fe/H] in the Galactic bulge, the Solar neighbourhood and Sagittarius, the type Ia supernova (SN) Mn yield must be metallicity-dependent.

Conclusions. We conclude that modelling different histories of star formation in the three systems are insufficient to reproduce the different behaviour of the [Mn/Fe] ratio, unlike the situation for [ α/Fe] ; rather, it is necessary to invoke metallicity-dependent type Ia SN Mn yields, as originally suggested by McWilliam, Rich & Smecker-Hane.