AAS Meeting #193 - Austin, Texas, January 1999
Session 105. Galaxy Kinematics and Dynamics
Display, Saturday, January 9, 1999, 9:20am-4:00pm, Exhibit Hall 1

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[105.06] Stellar Kinematics toward the South galactic Pole from the Southern Proper-Motion Program

Ren\'e A. M\'endez (Cerro Tololo Inter-American Observatory), W. F. van Altena, I. Platais, T. M. Girard, V. Kozhurina-Platais (Yale University), C. E. L\'opez (Universidad Nacional de San Juan)

We present a preliminary kinematic and color analysis of the randomly selected portion of the Yale/San Juan Southern Proper Motion Catalog 1.0, which covers an area of 720 deg2 toward the South Galactic Pole and includes more than thirty thousand stars in the magnitude range 9 \le B\rm J \le 20. The analysis is performed by comparing the observed color counts and absolute proper motion distributions to the predictions from a starcounts and kinematic model.

We model the star and color counts concurrently with the kinematics using a self-consistent approach that derives the mean rotational motion of each galactic component from its respective assumed spatial density law. We find that the color counts are very well matched by the model (as found from previous comparisons of the model to other photometric surveys at low, intermediate and high galactic latitudes), with the exception of an indication of a scale-height for disk Giants smaller than 250 pc, but still larger than the 150 pc minimum value found in the literature.

The kinematic model predictions are compared to the observed proper-motion distributions as a function of magnitude and color. We find that while the observed proper-motion dispersion is compatible with the velocity dispersions assumed in the model, and adopted from the literature, the component of the proper-motion along Galactic rotation implies a rather low value for the respective component of the solar peculiar motion, and a rather large rotational velocity for the LSR, relative to currently accepted values for these quantities. We note, however, that these results are in the same sense as, and in general agreement with, recent findings derived from the motions measured by the Hipparcos astrometric satellite.

The author(s) of this abstract have provided an email address for comments about the abstract: rmendez@noao.edu

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