The publicly available stellar database from SDSS contains many hundreds of metal-poor stars with large enhancements of carbon. The Galactic extension of SDSS, SEGUE, will identify several thousand more. Many of these Carbon-Enhanced Metal-Poor (CEMP) stars are likely to be enhanced in s-process elements created by AGB companions and dumped to the surviving member of a binary pair through either Roche-Lobe mass transfer or the operation of a stellar wind (CEMP-s stars). Based on previous high-resolution investigation of CEMP stars, an interesting subset of this sample is expected to show little or no s-process enhancement (CEMP-no stars).

Utilizing a novel technique of automatically fitting [Fe/H] and [C/Fe] for a large number of stars from SDSS through spectral synthesis methods, we are able to derive a new estimate of the frequency of CEMP stars as a function of metallicity for the largest sample of stars to date. Using this approach, we can also measure abundances (or limits) for species such as Sr and Ba, which can be used to roughly separate CEMP stars into the CEMP-s and CEMP-no classes.

We report on a dedicated effort to identify and study metal-poor stars that are strongly enhanced in r-process elements ($\mbox{[r/Fe]}>+1.0$dex; hereafter r-II stars), the Hamburg/ESO R-process Enhanced Star survey (HERES). In a sample of 253 confirmed metal-poor stars for which “snapshot” spectra ($R\sim 20,000$; $S/N \sim 50/1$ per pixel) were obtained with VLT/UVES, and abundances were determined in an automated fashion using the methods of Barklem et al. (2005), we identified eight new r-II stars. They are now being studied in detail by means of higher resolution and S/N spectroscopy. The new r-II stars have metallicities in the range $-3.2<\mbox{[Fe/H]}<-2.6$. Future searches for r-II stars should therefore focus on stars in this [Fe/H] range. Moderately r-process enhanced stars (i.e., $+0.3\,\mbox{dex}<\mbox{[r/Fe]}<+1.0\,\mbox{dex}$; r-I stars) were found at metallicities as high as $\mbox{[Fe/H]} = -1.5$. The [Fe/H] ranges in which r-I and r-II stars can be found may provide an important constraint for the identification of the site(s) of the r-process(es).

We present new carbon-enhanced stars identified from the third public release of the Sloan Digital Sky Survey, SDSS-DR3. We have generated synthetic spectra with varying carbon abundances, and compare them with the SDSS spectra. We have also performed a preliminary analysis of s-process enhancement in several SDSS carbon-enhanced stars. Spectral features that are sensitve to stellar luminosity and temperature have also been explored. These methods will be applied to the large set of public SDSS data, as well as to the forthcoming data from SEGUE, the Sloan Extension for Galactic Understanding and Evolution, in order to study carbon enhancement at different metallicities, the fraction of s-process enhancement that occurs in carbon-enhanced stars, and possibly isotopic carbon abundances and nitrogen abundances.

We present a determination of the lithium abundance from high quality spectra in an extremely metal poor star where the lithium line had not been detected.

Measurement of the abundances of the light and heavy elements in stars of the Milky Way galaxy is the cornerstone for the study of numerous aspects of chemical evolution in galaxies and the Universe. We stand poised to enter an era of rapid understanding, as new-generation telescopes with apertures in the 8m-10m class enable astronomers to obtain high-resolution, high-signal-to-noise near-UV, optical, and IR spectra of the stars which have locked up the chemical history of our Galaxy in their outer atmospheres. It is thus appropriate to review present surveys for the low-metallicity stars of our Galaxy, as the stars we uncover today will be studied so intensively in the coming decades.