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Origin of the Galactic Halo: accretion vs. in situ formation

Published online by Cambridge University Press:  02 August 2018

Emanuele Spitoni ,
Fiorenzo Vincenzo ,
Francesca Matteucci  and
Donatella Romano
Emanuele Spitoni
Affiliation:
Dipartimento di Fisica, Università di Trieste Via G. Tiepolo 11, 34131 Trieste, Italia email: spitoni@oats.inaf.it
Fiorenzo Vincenzo
Affiliation:
University of Hertfordshire, Hatfield, Hertfordshire, Hertfordshire, AL10 9AB, UK
Francesca Matteucci
Affiliation:
Dipartimento di Fisica, Università di Trieste Via G. Tiepolo 11, 34131 Trieste, Italia email: spitoni@oats.inaf.it INFN, Sezione di Trieste, via A. Valerio 2, 34127 Trieste, Italy
Donatella Romano
Affiliation:
INAF, Area della Ricerca - via Piero Gobetti, 101 - 40129 Bologna - ITALY
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Abstract

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We test the hypothesis that the classical and ultra-faint dwarf spheroidal satellites of the our Galaxy have been the building blocks of the Galactic halo by comparing their [O/Fe] and [Ba/Fe] vs. [Fe/H] patterns with the ones observed in Galactic halo stars. The [O/Fe] ratio deviates substantially from the observed abundance ratios in the Galactic halo stars for [Fe/H] > -2 dex, while they overlap for lower metallicities. On the other hand, for the neutron capture elements, the discrepancy is extended at all the metallicities, suggesting that the majority of stars in the halo are likely to have been formed in situ. We present the results for a model considering the effects of an enriched gas stripped from dwarf satellites on the chemical evolution of the Galactic halo. We find that the resulting chemical abundances of the halo stars depend on the adopted infall time-scale, and the presence of a threshold in the gas for star formation.

Keywords

ISM: abundances - Galaxy: abundances - Galaxy: evolution - Galaxy: halo
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 13 , Symposium S334: Rediscovering our Galaxy , July 2017 , pp. 34 - 37
Copyright
Copyright © International Astronomical Union 2018 

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