AAS 201st Meeting, January, 2003
Session 65. Stars and Galactic Structure in the Sloan Digital Sky Survey
Special, Tuesday, January 7, 2003, 2:00-3:30pm, 6AB

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[65.01] The Metallicities of SDSS Stars in the Halo and Thick Disk of the Galaxy -- Implications for Galaxy Formation

T.C. Beers (Michigan State University)

The database of stellar spectra that are now available in the Early Data Release (EDR), and which will be coming available over the course of the SDSS, provide valuable information concerning the nature of the various stellar populations in the Milky Way, in particular for the thick disk and halo of the Galaxy. The impact of the SDSS stellar spectra on our understanding of the Galaxy arises because of the (potentially) huge sample size, the spatial coverage of the SDSS, and the opportunity to select well-defined sub-samples of interesting stars based on their photometric properties.

The stellar spectra in the SDSS cover a wide range of S/N ratios, hence some effort must be made to develop tools that return estimates of interesting physical parameters of the stars that are robust when applied to data of variable quality. We describe our efforts to develop these tools, and present some preliminary results based on their application to the EDR stellar spectra, concentrating on the stars over the temperature range 4500 \le T\rm eff \le 7500 K. At present, we are able to obtain estimates of [Fe/H] and T\rm eff, as well as C/Fe ratios. Estimates of Ca/Fe, Mg/Fe, and Na/Fe should be feasible to obtain as well, once suitable calibrations have been carried out. It appears possible to obtain at least moderately accurate estimates of log g.

Although the stars in the EDR were selected for a variety of purposes, and hence are not completely suitable for statistical interpretation, there are indications that giants in the sample with distances more than 10 kpc from the Galactic center may exhibit a different metallicity distribution function than giants in the inner halo of the Galaxy, with profound implications for future searches for the most metal-deficient stars.

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

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