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T.C. Beers (Michigan State U.), M. Chiba (NAO, Japan), Y. Yoshii (IOA, Japan), I. Platais (Yale U.), R. Hanson (Lick Obs.), B. Fuchs (Heidelberg U., Germany), R. Williamson II (STScI)
In recent years, the numbers of recognized stars with metal abundances significantly less than solar has grown enormously. So too has the quality and quantity of information available concerning their detailed abundances, velocities, and proper motions. As a first-pass effort to demonstrate what new information can be obtained from study of this valuable database, we discuss a re-analysis of the kinematic properties of the N ~2000 non-kinematically selected stars with [Fe/H] \le -0.6 originally compiled by Beers & Sommer-Larsen (1995, ApJS, 96, 175).
Using newly determined (and/or refined) proper motions for over 1000 of these stars, based on results from the Hipparcos Satellite, the Southern Proper Motion Catalog 2.0, the Northern Proper Motion Catalog 1.0, the Astrographic Catalog, and the Digital Sky Survey obtained at STScI, we discuss our present view of the kinematics of the thick disk and halo components of the Milky Way galaxy. The newly obtained proper motions have more than doubled the numbers of stars with space motion determinations based on previous work of Chiba & Yoshii (1998, AJ, 115, 168) and Chiba, Yoshii, & Beers (1999, Third Stromlo Symposium, p. 273). A number of interesting differences are noted between the observed properties of this non-kinematically selected sample, as compared with similar-sized, but kinematically biased samples of metal-poor stars.
This work has received partial support from grant AST 95-29454 awarded by the National Science Foundation.
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