Broadband UBVR C I C Photometry of Horizontal-branch and Metal-poor Candidates from the HK and Hamburg/ESO Surveys. I
Date
2007
Authors
Beers, Timothy C
Flynn, Chris
Rossi, Silvia
Sommer-Larsen, Jesper
Wilhelm, Ronald
Marsteller, Brian
Sun Lee, Young
De Lee, Nathan
Krugler, Julie
Deliyannis, C P
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Volume Title
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IOP Publishing
Abstract
We report broadband UBVand/or BVRCIC CCD photometry for a total of 1857 stars in the thick-disk and halo populations of the Galaxy. The majority of our targets were selected as candidate field horizontal-branch or other A-type stars (FHB/A, N = 576), or candidate low-metallicity stars (N =1221), from the HK and Hamburg/ESO objective-prism surveys. Similar data for a small number of additional stars from other samples are also reported. These data are being used for several purposes. In the case of the FHB/A candidates they are used to accurately separate the lower gravity FHB stars from various higher gravity A-type stars, a subsample that includes the so-called blue metal poor stars, halo and thick-disk blue stragglers, main-sequence A-type dwarfs, and Am and Ap stars. These data are also being used to derive photometric distance estimates to high-velocity hydrogen clouds in the Galaxy and for improved measurements of the mass of the Galaxy. Photometric data for the metal-poor candidates are being used to refine estimates of stellar metallicity for objects with available medium-resolution spectroscopy, to obtain distance estimates for kinematic analyses, and to establish initial estimates of effective temperature for analysis of high-resolution spectroscopy of the stars for which this information now exists.
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Keywords
Keywords: Stars: early-type; Stars: horizontal-branch; Stars: Population II; Techniques: photometric
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Source
Astrophysical Journal, The
Type
Journal article
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2037-12-31
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