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Session 61 - Formation and Structure of the Milky Way.
Oral session, Tuesday, January 14
Harbour B,
Recent studies have shown that the halo is not a dynamically relaxed system. It is now likely that the origins and evolution of the Galaxy have been influenced if not entirely governed by the accretion of other stellar systems. This accretion causes structure likely to remain for extended lengths of time ( 1 Gyr) and so the phase space structure of the halo could be quite rich. Understanding such a chaotic structure will require access to all-sky surveys such as that of the Minnesota Automated Plate Scanner Catalog of POSS I.
We summarize our results for the structure of the halo and thick disk based on our analysis of star counts over large areas of the sky. These include the axial ratio of the halo and our recent discovery of a large asymmetry in the halo/thick disk star counts on either side of the galactic bulge at high latitudes. We also present a galactic model derived from star counts on large areas selected over the entire galactic sky covered by POSS I.
The author(s) of this abstract have provided an email address for comments about the abstract: larsen@isis.spa.umn.edu