Manganese evolution in Omega Centauri: a clue to the cluster formation mechanisms?

Abstract

We model the evolution of manganese relative to iron in the progenitor system of the globular cluster Omega Centauri by means of a self-consistent chemical evolution model. We use stellar yields that already reproduce the measurements of [Mn/Fe] versus [Fe/H] in Galactic field disc and halo stars, in Galactic bulge stars and in the Sagittarius dwarf spheroidal galaxy. We compare our model predictions to the Mn abundances measured in a sample of 10 red giant members and 6 subgiant members of Omega Cen. The low values of [Mn/Fe] observed in a few, metal-rich stars of the sample cannot be explained in the framework of our standard, homogeneous chemical evolution model. Introducing cooling flows that selectively bring to the cluster core only the ejecta from specific categories of stars does not help to heal the disagreement with the observations. The capture of field stars does not offer a viable explanation either. The observed spread in the data and the lowest [Mn/Fe] values could, in principle, be understood if the system experienced inhomogeneous chemical evolution. Such an eventuality is qualitatively discussed in the present paper. However, more measurements of Mn in Omega Cen stars are needed to settle the issue of Mn evolution in this cluster.

8 pages, 4 figures, accepted for publication in MNRAS

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Cited by in corpus (7)

• Detailed abundance analysis from integrated high-dispersion spectroscopy: Globular clusters in the Fornax Dwarf Spheroidal
• Manganese in dwarf spheroidal galaxies
• The AMBRE project: Iron-peak elements in the solar neighbourhood
• Chemical evolution of Local Group dwarf galaxies in a cosmological context -- I. A new modelling approach and its application to the Sculptor dwarf spheroidal galaxy
• Subclasses of Type Ia Supernovae as the origin of [α/Fe] ratios in dwarf spheroidal galaxies
• Chemical Abundances of Globular Clusters in NGC 5128 (Centaurus A)
• A new formation model for omega Centauri: the crossroad of astrophysical processes