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UBC Theses and Dissertations

Constraining the form of the galactic halo with deep star counts Davis, David Sau


The Canada-France-Hawaii Telescope Legacy Survey - Deep (CFHTLS-Deep) represents a truly unique data set in terms of angular size and depth. Although the survey is only ~ 40% complete, it is already complete to a magnitude of 25 in u*,g',r',i', and z'. We use this data for an ambitious star-count project. By comparing the observed colourmagnitude diagrams (CMDs) with simulated CMDs, one can place many constraints on the form of the Galaxy. This thesis represent the first stage of this project - the study of the stellar halo of the Galaxy. We find the half-light radius of the de Vaucouleurs profile to be slightly higher than the literature value. We find the slope of the initialmass function of stars with masses between 0.4 MQ < M < 0.8M© is slightly lower than Salpeter. We find that the halo is oblate with a ratio of minor axis to major axis of ~ 0.9. Finally, we find that the best value of the stellar binary fraction is 0.35. The other elements of the CFHTLS (CFHTLS-Wide and CFHTLS-Very Wide) provide an immense number of observations that can be compared with theoretical models. There is plenty of data with which to constrain the form of the other components of the Galaxy - the thick and thin disks. This study, along with the subsequent studies, will give us the most detailed picture of the stars in our home Galaxy ever.

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