P. François, L. Monaco, S. Villanova, M. Catelan, P. Bonifacio, M. Bellazzini, C. Moni Bidin, G. Marconi, D. Geisler, L. Sbordone
We report preliminary results concerning the detailed chemical composition of
metal poor stars belonging to close ultra-faint dwarf galaxies (hereafter
UfDSphs). The abundances have been determined thanks to spectra obtained with
X-Shooter, a high efficiency spectrograph installed on one of the ESO VLT
units. The sample of ultra-faint dwarf spheroidal stars have abundance ratios
slightly lower to what is measured in field halo star of the same
metallicity.We did not find extreme abundances in our Hercules stars as the one
found by Koch for his 2 Hercules stars. The synthesis of the neutron capture
elements Ba and Sr seems to originate from the same nucleosynthetic process in
operation during the early stages of the galactic evolution.
View original:
http://arxiv.org/abs/1202.2899
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