Bibcode
Rockosi, C. M.; Beers, T. C.; Allende Prieto, C.; Wilhelm, R.; Sloan Digital Sky Survey Collaboration
Bibliographical reference
American Astronomical Society Meeting 203, #112.10; Bulletin of the American Astronomical Society, Vol. 35, p.1385
Advertised on:
12
2003
Citations
0
Refereed citations
0
Description
The structure and evolution of the Milky Way is imprinted on the
kinematics, chemical abundances, and spatial distribution of its
constituent stars. In the past, samples of stars in the halo and thick
disk have primarily been selected either on the basis of their
kinematics (e.g., proper-motion selection), their distinct abundances
(e.g., objective-prism selection of metal-poor stars), or their unusual
colors (e.g., via δ (U-B)). As a result, it has been difficult to
confidently infer a unbiased picture of the underlying chemo-dynamical
properties of the of these populations.
We present an analysis of the kinematics of the thick disk and the halo
based on a sample of 1200 stars from two high-latitude fields for which
we have measured radial velocities, proper motions, chemical abundances,
and derived estimates of Teff and log(g), based on
flux-calibrated medium-resolution spectroscopy and five-band ugriz
photometry obtained from the Sloan Digital Sky Survey (SDSS). The stars
are randomly chosen in the range g-r < 0.8, r < 19.15, and lie
near the main-sequence turnoff of ancient stellar populations at
distances between 1 and 10 kpc from the sun. They are selected without
regard to their kinematics or chemical composition, and so represent a
fair sample of the stellar populations from which they are drawn. We use
this nearly ideal dataset to examine the correlation between kinematics,
chemical abundance, and position in the Galaxy along these lines of
sight. We compare the velocity and chemical abundance information with
the global properties of the thick disk and halo as traced by the
main-sequence turnoff color in the SDSS photometry, and with models for
the thick disk and halo fit to SDSS color magnitude diagrams.
These data represent the first 10% of a much larger sample we are in the
process of assembling. Future surveys of Galactic stars, such as might
be obtained by the proposed SEGUE extension to SDSS, will enable
unprecedented knowledge of the nature of the thick-disk, and the inner
and outer halo populations of the Milky Way.
This work has received partial support from NSF grants AST 00-98508 and
AST 00-98549 and NASA grant HST-HF-01143.01-A.