AAS Meeting #194 - Chicago, Illinois, May/June 1999
Session 84. Studying the Anatomy of the Milky Way
Display, Thursday, June 3, 1999, 9:20am-4:00pm, Southwest Exhibit Hall

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[84.05] Faint A stars as tracers of the structure of the Galactic Halo

B. Yanny, H. Newberg (Fermi National Accelerator Laboratory), R. H. Becker (University of California, Davis), S. Laurent-Muehleisen (LLNL), J. R. Pier (USNO, Flagstaff), G. Richards (University of Chicago), Sloan Digital Sky Survey Collaboration

Number counts of over 2000 stellar objects with A-star colors to 20th magnitude in the Galaxy obtained from SDSS engineering data indicates an excess in the number of these objects over any prediction from previously observed halo density profiles for visible stars. The number counts of these objects out to implied distances greater than 40 kpc appears to follow a law closer to that of rho(r) ~ r-2.5 rather than any steeper law such as the r-3.5 followed for other populations. There is evidence that not all the objects at large distances from the Galactic Center with these colors are horizontal branch stars, as several have spectra showing gravities consistent with those of main sequence A stars. We measure the clustering properties of these stars.


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