Research Note

Discovery of a variable star population in NGC 2808

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

Corresponding author: M. Catelan, mcatelan@astro.puc.cl

Received: 23 December 2003
Accepted: 14 April 2004

Abstract

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.