Research Note

New variable stars in open clusters^*

I. Methods and results for 20 open clusters

¹ Institut für Astronomie der Universität Wien, Türkenschanzstr. 17, 1180 Wien, Austria
² Zentraler Informatikdienst der Universität Wien, Universitätsstr. 7, 1010 Wien, Austria
³ Departamento de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, Argentina – Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina

Corresponding author: E. Paunzen, Ernst.Paunzen@univie.ac.at

Received: 4 November 2003
Accepted: 3 February 2004

Abstract

We present high precision CCD photometry of 1791 objects in 20 open clusters with an age of 10 Myr to 1 Gyr. These observations were performed within the photometric system which is primarily used to detect chemically peculiar stars of the upper main sequence. Time bases range from 30 min up to 60 days with data from several nights. We describe the time series analysis reaching a detection limit of down to 0.006 mag for apparent variability. In total, we have detected 35 variable objects of which four are not members of their corresponding clusters. The variables cover the entire Hertzsprung-Russell diagram, hence they are interesting targets for follow-up observations.