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Volume 421, Number 2, July II 2004
Page(s) 667 - 672
Section Galactic structure, stellar clusters and populations
DOI https://doi.org/10.1051/0004-6361:20035944

A&A 421, 667-672 (2004)
DOI: 10.1051/0004-6361:20035944

Research Note

Discovery of a variable star population in NGC 2808

T. Michael Corwin1, M. Catelan2, J. Borissova2 and H. A. Smith3

1  Department of Physics, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
    e-mail: mcorwin@uncc.edu
2  Pontificia Universidad Católica de Chile, Departamento de Astronomía y Astrofísica, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago, Chile
    e-mail: [mcatelan;jborisso]@astro.puc.cl
3  Dept. of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
    e-mail: smith@pa.msu.edu

(Received 23 December 2003 / Accepted 14 April 2004)

We have applied the image subtraction method to images of the peculiar, bimodal-horizontal branch globular cluster NGC 2808, taken over a total of six nights over a range of five months. As a result, we have found, for the first time, a sizeable population of variable stars in the crowded inner regions of the cluster, thus raising the known RR Lyrae population in the cluster to a total of 18 stars. In addition, an eclipsing binary and two other variables with periods longer than 1 day were also found. Periods, positions and (differential) light curves are provided for all the detected variables. The Oosterhoff classification of NGC 2808, which has recently been associated with a previously unknown dwarf galaxy in Canis Major, is briefly discussed.

Key words: Galaxy: globular clusters: individual: NGC 2808 -- stars: horizontal-branch -- stars: variables: RR Lyr

Offprint request: M. Catelan, mcatelan@astro.puc.cl

© ESO 2004