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W. R. Brown (Harvard-Smithsonian CfA), M. J. Geller, S. Kenyon, M. Kurtz (SAO), T. Beers (MSU), C. Allende Prieto (UT), R. Wilhelm (TTU)
The Century Survey is a photometric survey strip from which we select blue stars to probe the Milky Way halo. We obtain S/N=30 spectra for every star with (V-R)<0.25 and V<16.5 mag in the 1\circ \times 64\circ Century Survey strip, and for every star with (J-H)<0.15 and J<15 mag in an adjacent 1\circ \times 64\circ 2MASS region. The Century Survey is placed along a roughly constant line of galactic longitude and spans 35\circ < b < 88\circ. This placement allows us to measure populations of stars and their systematic motions as a function of galactic latitude. One of our primary goals is to use blue horizontal branch stars to trace potential star streams in the halo and test the hierarchal picture for the formation of the Galaxy.
We present a sample of 764 stars from the Century Survey. We measure radial velocities, abundances, effective temperatures,surface gravities, and other physical parameters from the spectra. Approximately half of the stars are F-types located in the thick disk. The other half of the stars are A-types with a ±105 km s-1 velocity dispersion consistent with a halo population. We use three methods to distinguish blue horizontal branch from higher surface gravity A-type stars, and identify 54 blue horizontal branch stars to r=15 kpc in our sample. We look for associations in velocity, abundance, and position. In addition, we find a small number of unusual objects in the Century Survey, including white dwarfs, quasars, and B-type stars at modest distances above the Galactic plane.
The author(s) of this abstract have provided an email address for comments about the abstract: wbrown@cfa.harvard.edu
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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.