Halo Substructure: Clues to the Merger History of the Milky Way

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AST-0507364INSTITUTION: Yale UniversityPI: Robert ZinnTITLE: Halo Substructure - Clues to the Merger History of the Milky WayABSTRACTDr. Robert Zinn, of Yale University, will undertake a program to complete three surveys, using RR Lyrae stars, to probe Galactic halo substructure. One survey will probe roughly twice the volume of the halo to the same ~60 kpc distance from the Sun as the first QUEST survey. A second survey, the Palomar-QUEST survey, will probe a significantly greater volume to a distance of roughly 100 kpc. The third survey is directed toward a dwarf galaxy in Canis Major that appears to be undergoing tidal disruption. Dr. Zinn will also undertake spectroscopic observations of the substructures detected by these surveys to establish if the stars are moving groups, to search for moving groups where there is no obvious substructure, and to measure more precisely the properties of the stream from the Sagittarius dwarf galaxy, which has the potential of constraining the distribution of dark matter in the halo. The primary broader impact of the research is in the areas of graduate and undergraduate student education and international collaboration. Dr. Zinn also participates in public outreach activities, including lectures to adults and Boy Scouts, as well as visits to elementary and secondary school classrooms.