EDP Sciences
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Volume 375, Number 2, August IV 2001
Page(s) 366 - 374
Section Galactic structure and dynamics
DOI http://dx.doi.org/10.1051/0004-6361:20010814

A&A 375, 366-374 (2001)
DOI: 10.1051/0004-6361:20010814

The stellar content of the Hamburg/ESO survey

II. A large, homogeneously-selected sample of high latitude carbon stars
N. Christlieb1, P. J. Green2, L. Wisotzki3 and D. Reimers1

1  Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
    e-mail: dreimers@hs.uni-hamburg.de
2  Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02140, USA
    e-mail: pgreen@cfa.harvard.edu
3  Institut für Physik, Universität Potsdam, Am Neuen Palais 10, 14469 Potsdam, Germany
    e-mail: lutz@astro.physik.uni-potsdam.de

(Received 26 April 2001 / Accepted 5 June 2001 )

We present a sample of 403 faint high latitude carbon (FHLC) stars selected from the digitized objective prism plates of the Hamburg/ESO Survey (HES). Because of the $\sim $15 Å spectral resolution and high signal-to-noise ratio of the HES prism spectra, our automated procedure based on the detection of C2 and CN molecular bands permits high-confidence identification of carbon stars without the need for follow-up spectroscopy. From a set of 329 plates (87 % of the survey), covering 6 400 deg2 to a magnitude limit of $V\sim16.5$, we analyze the selection efficiency and effective surface area of the HES FHLC survey to date. The surface density of FHLC stars that we detect ( $0.072\pm 0.005$ deg-2) is 2-4 times higher than that of previous objective prism and CCD surveys at high galactic latitude, even though those surveys claimed a limiting magnitude up to 1.5 magnitudes fainter. This attests to the highest selection sensitivity yet achieved for these types of stars.

Key words: stars: carbon -- surveys -- Galaxy: halo

Offprint request: N. Christlieb, nchristlieb@hs.uni-hamburg.de

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