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Reading the Chemical Evolutionary Signatures of Dwarf Spheroial Galaxies

Ben Hendricks (Heidelberg)

Évènements associés

  • Le lundi 2 juin 2014 de 11:00 à 12:00 - lieu : Salle 108, Bâtiment des Communs - Meudon

Dwarf spheroidal (dSph) galaxies are the smallest, closest and most abundand galaxies in the Universe and therefore excellent laboratories to study star formation (SF) history and chemical evolution on the smallest scale. Particularly the newest generation of multi-object spectrographs have helped to unveil details about their dynamical and chemical properties in the last couple of years. However, there is still a lack of sufficiently large, homogeneous spectroscopic datasets for sufficiently many individual dSphs, and therefore we are just beginning to understand the physical concepts behind the observed properties. Here, I present chemical abundances for iron (Fe) and three alpha-elements (Mg, Si, Ti) from high-resolution spectra for a large sample of field stars in the Fornax dSph. For the first time, we are able to resolve and trace the chemical evolution of Fornax over almost its entire age. Surprisingly, we find that Fornax experienced a very weak star formation efficiency at early times, not in agreement with either direct comparisons of observations in other dSphs, nor with chemical evolutionary models. The scope of this talk is to present the results from our chemical analysis and put them in a general context of our understanding of chemical evolution in dSphs, and its key-regulating factors. On this basis, possible (and impossible) evolutionary scenarios for Fornax are discussed and compared with model predictions.