A Spectroscopic Study of the Ancient Milky Way: F‐ and G‐Type Stars in the Third Data Release of the Sloan Digital Sky Survey
Year: 2006
Type: article
Abstract: We perform an analysis of spectra and photometry for 22,770 stars included in the third data release (DR3) of the Sloan Digital Sky Survey (SDSS). We derive atmospheric parameters and distances. Our analysis procedures are throughly checked using three recently published spectroscopic libraries of nearby stars and alternative methods. The SDSS sample covers a range in stellar brightness of 14 < V < 22, primarily at intermediate Galactic latitudes, and comprises large numbers of F- and G-type stars from the thick-disk and halo populations, therefore including some of the oldest stars in the Milky Way. We find that halo stars exhibit a broad range of iron abundances, with a peak at [Fe/H] ≃ -1.4. This population exhibits essentially no Galactic rotation. Thick-disk G-dwarf stars at distances from the Galactic plane in the range 1 < | z | < 3 kpc show a much more compact metallicity distribution, with a maximum at [Fe/H] ≃ -0.7, and a median Galactic rotation lagging the local standard of rest by 63 km s -1 . A comparison of color indices and metal abundances with isochrones indicates that no significant star formation has taken place in the halo in the last ~11 Gyr, but there are thick-disk stars that are at least 2 Gyr younger. We find the metallicities of thick-disk stars to be nearly independent of Galactocentric distance between 5 and 14 kpc from the Galactic center, in contrast with the marked gradients found in the literature for the thin disk. No vertical metallicity gradient is apparent for the thick disk, but we detect a gradient in its rotational velocity of -16 ± 4 km s -1 kpc -1 between 1 and 3 kpc from the plane. We estimate that among the stars in our sample there are over 2000 with an iron abundance [Fe/H] < -2, and over 150 stars with an iron abundance [Fe/H] < -3.
Source: The Astrophysical Journal
DOI: 10.1086/498131
Authors: Carlos Allende Prieto, Timothy C. Beers, Ronald Wilhelm, Heidi Jo Newberg, Constance M. Rockosi, Brian Yanny, Young Sun Lee
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funders: National Science Foundation, U.S. Department of Energy, National Aeronautics and Space Administration, Alfred P. Sloan Foundation, Princeton University, University of Washington, Johns Hopkins University, University of Pittsburgh, New Mexico State University, Max-Planck-Gesellschaft, Max-Planck-Institut für Astronomie, U.S. Naval Observatory, Fermilab, Los Alamos National Laboratory
Awards: AN AUTOMATED TOOL FOR MINING THE IUE ARCHIUVE, G3258415740, The Nature of Metal-Poor Carbon-Enhanced Stars in the Galaxy, NON-LTE MODEL ATMOSPHERES AND THEIR IMPACT ON OBSE RVATIONAL STUDIES OF GALACTIC CHEMICAL EVOLUTION, Joint Institute for Nuclear Astrophysics - JINA, Data Mining the Galatic Sky- Identifying Substructure in the Outer Parts of the Milky Way, An Intensive Search for r-process-Enhanced Stars, and Abundance Patterns in the Early Galaxy, Collaborative Research: Completion of the Southern Proper Motion Program
OpenAlex ID: W1974517839