Program: GS-2008B-Q-33

Title:Chemical Evolution in the Sagittarius Stream
PI:Stefan Keller
Co-I(s): Gary Da Costa, David Yong, Kenneth Freeman, Michael Bessell

Abstract

We seek to determine the metallicity and [alpha/Fe] ratio for M-giants in the trailing arm of the Sagittarius dwarf debris stream. Our targets sample the chemistry of the trailing arm in two regions and, therefore, at two epochs (~1Gyr and ~2Gyrs since tidal disruption). By comparison to each other, and extant samples of the main body of the dSph, we will develop a unique view of the evolution of the metallicity distribution function and [alpha/Fe] in an accretion event. This proposal seeks to shed light on an outstanding difficulty for Lambda CDM hierarchical structure formation: if the halo is composed of accreted dSph why is [alpha/Fe] high in the halo and low in dSphs?

Publications using this program's data