Close binary and other variable stars in the solar-age Galactic open cluster M 67*
Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
2 University of Cambridge, Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK e-mail: firstname.lastname@example.org
3 University of Ege, Department of Astronomy & Space Sciences, 35100 Izmir, Turkey
4 Izmir Institute of Technology, Department of Physics, 35430 Izmir, Turkey
5 Royal Observatory of Belgium, Ringlaan 3, 1180 Brussel, Belgium
6 LPNHE – Université Paris, 75252 Paris Cedex 05, France
7 TÜBİTAK National Observatory, Antalya, Turkey
8 IMAPP, Radboud Universiteit Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands
Accepted: 5 June 2009
We present multi-colour time-series CCD photometry of the solar-age galactic open cluster M 67 (NGC 2682). About 3600 frames spread over 28 nights were obtained with the 1.5 m Russian-Turkish and 1.2 m Mercator telescopes. High-precision observations of the close binary stars AH Cnc, EV Cnc, ES Cnc, the δ Scuti type systems EX Cnc and EW Cnc, and some long-period variables belonging to M 67 are presented. Three full multi-colour light curves of the overcontact binary AH Cnc were obtained during three observing seasons. Likewise we gathered three light curves of EV Cnc, an EB-type binary, and two light curves of ES Cnc, a blue straggler binary. Parts of the light change of long-term variables S1024, S1040, S1045, S1063, S1242, and S1264 are obtained. Period variation analysis of AH Cnc, EV Cnc, and ES Cnc were done using all times of mid-eclipse available in the literature and those obtained in this study. In addition, we analyzed multi-colour light curves of the close binaries and also determined new frequencies for the δ Scuti systems. The physical parameters of the close binary stars were determined with simultaneous solutions of multi-colour light and radial velocity curves. Finally we determined the distance of M 67 as 857(33) pc via binary star parameters, which is consistent with an independent method from earlier studies.
Key words: binaries: close / binaries: eclipsing / stars: oscillations / open clusters and associations: individual: M 67
Based on observations made with the Mercator Telescope, operated on the island of La Palma by the Flemish Community, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias and TÜBİTAK National Observatory Russian-Turkish telescope operated at Saklıkent, Antalya.
© ESO, 2009