Journal Article

SEGUE-2: Old Milky Way Stars Near and Far

Gunn, James E, Blanton, Michael R, An, Deokkeun, López-Corredoira, Martín, Kollmeier, Juna A, Lépine, Sébastien, Eisenstein, Daniel J, Casagrande, Luca, Lucatello, Sara, Janesh, William, Ivans, Inese I, Rockosi, Constance M, Yanny, Brian, Allende Prieto, Carlos, Newberg, Heidi J, Knapp, Gillian R, Prchlik, Jakub, Morrison, Heather L, Gould, Andrew, Simmerer, Jennifer, Sobeck, Jennifer, Schlesinger, Katharine J, Pan, Kaike, Weinberg, David H, Sun Lee, Young, Bizyaev, Dmitry, Harding, Paul, Ma, Zhibo, Sayers, Conor, Johnson, Jennifer A, Jacobson, H. R, Beers, Timothy C

2022

Overview

The Sloan Extension for Galactic Understanding and Exploration 2 (SEGUE-2) obtained 128,288 low-resolution spectra (R ∼ 1800) of 118,958 unique stars in the first year of the Sloan Digital Sky Survey III (2008–2009). SEGUE-2 targeted prioritized distant halo tracers (blue horizontal-branch stars, K giants, and M giants) and metal-poor or kinematically hot populations. The main goal of SEGUE-2 was to target stars in the distant halo and measure their kinematics and chemical abundances to learn about the formation and evolution of the Milky Way. We present the SEGUE-2 field placement and target selection strategies. We discuss the success rate of the targeting based on the SEGUE-2 spectra and other spectroscopic and astrometric surveys. We describe the final SEGUE-2/SDSS-III improvements to the stellar parameter determinations based on the SEGUE Stellar Parameter Pipeline. We report a (g − i) color−effective temperature relation calibrated to the IRFM. We evaluate the accuracy and uncertainties associated with these stellar parameters by comparing with fundamental parameters, a sample of high-resolution spectra of SEGUE stars analyzed homogeneously, stars in well-studied clusters, and stars observed in common by the APOGEE survey. The final SEGUE spectra, calibration data, and derived parameters described here were released in SDSS-III Data Release 9 and continue to be included in all subsequent SDSS Data Releases. Because of its faint limiting magnitude and emphasis on the distant halo, the public SEGUE-2 data remain an important resource for the spectroscopy of stars in the Milky Way.

• Publisher: IOP Publishing
• Subject: Apogees / Horizontal branch stars / Kinematics / Metallicity / Milky Way / Parameters / Sky surveys (astronomy) / Spectra / Spectroscopy / Spectrum analysis / Stars / Tracers