The Century Survey Galactic Halo Project I: Stellar Spectral Analysis

Abstract

The Century Survey Galactic Halo Project is a photometric and spectroscopic survey from which we select relatively blue stars (V-R<0.30 mag) as probes of the Milky Way halo. The Survey strip spans the range of Galactic latitude 35<b<88 deg, allowing us to study the nature of populations of stars and their systematic motions as a function of Galactic latitude. One of our primary goals is to use blue horizontal-branch stars to trace potential star streams in the halo, and to test the hierarchical model for the formation of the Galaxy. In this paper we discuss spectroscopy and multi-passband photometry for a sample of 764 blue stars in the Century Survey region. Our sample consists predominantly of A- and F-type stars. We describe our techniques for determination of radial velocities, effective temperatures, metallicities, and surface gravities. Based on these measurements, we derive distance estimates by comparison with a set of calibrated isochrones. We devote special attention to the classification of blue horizontal-branch stars, and compare the results obtained from the application of the techniques of Kinman et al., Wilhelm et al., and Clewley et al. We identify 55 blue horizontal-branch stars. Our large sample of stars also uncovers a number of unusual objects, including three carbon-enhanced stars, a late B-type star located 0.8 kpc above the Galactic plane, and a DZ white dwarf.

19 pages, including 11 figures. Full data tables on request from W.R.B. Accepted by AJ

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Cited by in corpus (19)

• A Spectroscopic Study of the Ancient Milky Way: F- and G-Type Stars in the Third Data Release of the Sloan Digital Sky Survey
• Discovery of an Unbound Hyper-Velocity Star in the Milky Way Halo
• Hypervelocity Stars. I. The Spectroscopic Survey
• A Successful Targeted Search for Hypervelocity Stars
• Velocity Dispersion Profile of the Milky Way Halo
• Hypervelocity Stars III. The Space Density and Ejection History of Main Sequence Stars from the Galactic Center
• Hypervelocity Stars II. The Bound Population
• Shedding Light on the Galaxy Luminosity Function
• Broadband UBVRI Photometry of Horizontal-Branch and Metal-Poor Candidates from the HK and Hamburg/ESO Surveys. I
• MMT Hypervelocity Star Survey. II. Five New Unbound Stars
• The Century Survey Galactic Halo Project III: A Complete 4300 deg^2 Survey of Blue Horizontal Branch Stars in the Metal-Weak Thick Disk and Inner Halo
• The Kinematic Properties of BHB and RR Lyrae stars towards the Anticentre and the North Galactic Pole: The Transition between the Inner and the Outer Halo
• Kinematic Structure in the Galactic Halo at the North Galactic Pole: RR Lyrae and BHB Stars show different kinematics
• The ILIUM forward modelling algorithm for multivariate parameter estimation and its application to derive stellar parameters from Gaia spectrophotometry
• Distant field BHB stars and the mass of the Galaxy II: Photometry and spectroscopy of UKST candidates 16<B<19.5, 11<R<52 kpc
• Stellar Velocity Dispersion and Anisotropy of the Milky Way Inner Halo
• Surveying the Inner Halo of the Galaxy with 2MASS-Selected Horizontal Branch Candidates
• The Century Survey Galactic Halo Project II: Global Properties and the Luminosity Function of Field Blue Horizontal Branch Stars
• Center for Astrophysics Optical Infrared Science Archive. I. FAST Spectrograph