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24th of August 2016
ATNF Colloquium
Globular clusters and halo assembly
by Sarah Martell (UNSW)
Abstract. Hierarchical accretion models for galaxy formation predict that the majority of stars in the halo of a spiral galaxy should have formed within dwarf galaxies that were later accreted by the larger galaxy. In 2010, we used a rough chemical tagging approach to identify stars in the Milky Way halo that had likely formed in globular clusters, using the light-element abundance anomalies that are well-studied in Galactic globular clusters. This was the first identification of this population of halo stars that formed in situ, and subsequent studies have confirmed our initial result. Ideally one would use this chemically taggable population, which comprises around 2.5% of the halo, to explore the importance of in situ star formation in halo assembly. However, the interpretation is strongly dependent on models for globular cluster formation, mass loss, and dissolution. I will present a new search for globular cluster migrants in the Galactic halo in SDSS-III APOGEE survey data, and discuss the interpretation of this population in the light of recent theoretical work on globular cluster formation that is upending many previous assumptions.

Image credit: Bullock & Johnston 2005

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