Photometric study of selected cataclysmic variables

¹ Royal Observatory of Belgium, Avenue Circulaire 3, 1180 Brussels, Belgium e-mail: Christina.Papadaki@oma.be
² Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
³ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85738 Garching, Germany
⁴ Physics Department, Stockholm University, AlbaNova University Centre, 106 91 Stockholm, Sweden
⁵ Institute of Astronomy & Astrophysics, National Observatory of Athens, I. Metaxa & V. Pavlou, P. Penteli, 15236 Athens, Greece
⁶ University of Crete, Physics Department, 71003 Heraklion, Crete, Greece
⁷ Astronomical Laboratory, Department of Physics, University of Patras, 26500 Rio–Patras, Greece

Received: 12 December 2005
Accepted: 26 March 2006

Abstract

Aims.We present time-resolved photometry of five relatively poorly-studied cataclysmic variables: V1193 Ori, LQ Peg, LD 317, V795 Her, and MCT 2347-3144.

Methods.The observations were made using four 1m-class telescopes for a total of more than 250 h of observation and almost 16 000 data points. For LQ Peg WHT spectroscopic data have been analysed as well.

Results.The light curves show a wide range of variability on different time scales from minutes to months. We detect for the first time a brightness variation of 0.05 mag in amplitude in V1193 Ori on the same timescale as the orbital period, which we interpret as the result of the irradiation of the secondary. A 20-min quasi-periodic oscillation is also detected. The mean brightness of the system has changed by 0.5 mag on a three-month interval, while the flickering was halved. In LQ Peg a 0.05 mag modulation was revealed with a period of about 3 h. The flickering was much smaller, of the order of 0.025 mag. A possible quasi-periodic oscillation could exist near 30 min. For this object, the WHT spectra are single-peaked and do not show any radial-velocity variations. The data of LD 317 show a decrease in the mean magnitude of the system. No periodic signal was detected but this is certainly attributable to the very large flickering observed: between 0.07 and 0.1 mag. For V795 Her, the 2.8-h modulation, thought to be a superhump arising from the precession of the disc, is present. We show that this modulation is not stable in terms of periodicity, amplitude, and phase. Finally, for MCT 2347-3144, a clear modulation is seen in a first dataset obtained in October 2002. This modulation is absent in August 2003, when the system was brighter and showed much more flickering.