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N.A. Bond, Z. Ivezic, M. Juric, J.A. Munn, R.H. Lupton, D. Schlegel, D. Finkbeiner, C.M. Rockosi, J.R. Knapp, J.E. Gunn, B. Yanny ()
We analyze the Milky Way kinematics using a sample of 30 million stars with proper motion measurements derived from SDSS and POSS astrometry. 200,000 of these stars have radial velocity measurements from the SDSS spectroscopic survey. These predominantly main sequence stars sample a distance range from 100 pc to 15 kpc, at high galactic latitude, and allow a detailed and robust determination of the velocity field as a function of location. We find that in the region 50 pc < Z < 5 kpc, 3 < R < 13 kpc, the rotational velocity and its dispersion for disk stars smoothly increase with distance from the galactic plane. In contrast, for low-metalicity stars selected by their u-g color, both quantities appear independent of Z. The velocity distribution for small subsamples limited by volume and metallicity is often strongly nongaussian and at odds with standard models.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.