The stellar content of the Hamburg/ESO survey ^*,**

III. Field horizontal-branch stars in the Galaxy

¹ Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany e-mail: [nchristlieb;dreimers]@hs.uni-hamburg.de
² Department of Physics & Astronomy and JINA: Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA e-mail: beers@pa.msu.edu
³ Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, VIC 3122, Australia e-mail: cthom@astro.swin.edu.au
⁴ Department of Physics, Texas Tech University, Lubbock, TX 79409, USA e-mail: ron.wilhelm@ttu.edu
⁵ Departamento de Astronomia Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, 05508-900 São Paulo SP, Brazil e-mail: rossi@astro.iag.usp.br
⁶ Tuorla Observatory, University of Turku, Väisäläntie 20, 21500 Piikkiö, Finland e-mail: cflynn@utu.fi
⁷ Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany e-mail: lutz@aip.de

Received: 11 August 2004
Accepted: 20 October 2004

Abstract

We present a sample of 8321 candidate Field Horizontal-Branch (FHB) stars selected by automatic spectral classification in the digital data base of the Hamburg/ESO objective-prism survey. The stars are distributed over 8225 square degrees of the southern sky, at . The average distance of the sample, assuming that they are all FHB stars, is 9.8 kpc, and distances of up to ∼30 kpc are reached. Moderate-resolution spectroscopic follow-up observations and UBV photometry of 125 test sample stars demonstrate that the contamination of the full candidate sample with main-sequence A-type stars is <16%, while it would be up to 50% in a flux-limited sample at high galactic latitudes. Hence more than 6800 of our FHB candidates are expected to be genuine FHB stars. The candidates are being used as distance probes for high-velocity clouds and for studies of the structure and kinematics of the Galactic halo.