Broadband UBVRCIC photometry of horizontal-branch and metal-poor candidates from the HK and Hamburg/ESQ surveys. I.

Timothy C. Beers, Chris Flynn, Silvia Rossi, Jesper Sommer-Larsen, Ronald Wilhelm, Brian Marsteller, Young Sun Lee, Nathan De Lee, Julie Krugler, Constantine P. Deliyannis, Andrew T. Simmons, Elisabeth Mills, Franz Josef Zickgraf, Johan Holmberg, Anna Önehag, Anders Eriksson, Donald M. Terndrup, Samir Salim, Johannes Andersen, Birgitta NordströmNorbert Christlieb, Anna Frebel, Jaehyon Rhee

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

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.

Original languageEnglish
Pages (from-to)128-139
Number of pages12
JournalAstrophysical Journal, Supplement Series
Volume168
Issue number1
DOIs
StatePublished - Jan 2007

Keywords

  • Stars: Population II
  • Stars: early-type
  • Stars: horizontal-branch
  • Techniques: photometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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