HS 0139+0559, HS 0229+8016, HS 0506+7725, and HS 0642+5049: four new long-period cataclysmic variables

¹ Department of Physics, University of Warwick, Coventry CV4 7AL, UK e-mail: A.Aungwerojwit@warwick.ac.uk
² Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
³ Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
⁴ Institute of Space Applications and Remote Sensing, National Observatory of Athens, PO Box 20048, Athens 11810, Greece
⁵ Institute of Astronomy and Astrophysics, National Observatory of Athens, PO Box 20048, Athens 11810, Greece
⁶ Department of Astrophysics, Astronomy and Mechanics, University of Athens, 157 84 Zografos, Athens, Greece
⁷ Department of Physics, 20014 University of Turku, Finland
⁸ Tuorla Observatory, University of Turku, 21500 Piikkiö, Finland
⁹ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD21218, USA
¹⁰ Astronomisches Institut der Universität Erlangen, Germany
¹¹ Braeside Observatory, PO Box906, Flagstaff, AZ 86002, USA

Received: 23 December 2004
Accepted: 3 July 2005

Abstract

We present time-resolved optical spectroscopy and photometry of four relatively bright () long-period cataclysmic variables (CVs) discovered in the Hamburg Quasar Survey: HS 0139+0559, HS 0229+8016, HS 0506+7725, and HS 0642+5049. Their respective orbital periods,  min,  min,  min, and  min are determined from radial velocity and photometric variability studies. HS 0506+7725 is characterised by strong Balmer and He emission lines, short-period (~ min) flickering, and weak X-ray emission in the ROSAT All Sky Survey. The detection of a deep low state () identifies HS 0506+7725 as a member of the VY Scl stars. HS 0139+0559, HS 0229+8016, and HS 0642+5049 display thick-disc like spectra and no or only weak flickering activity. HS 0139+0559 and HS 0229+8016 exhibit clean quasi-sinusoidal radial velocity variations of their emission lines but no or very little orbital photometric variability. In contrast, we detect no radial velocity variation in HS 0642+5049 but a noticeable orbital brightness variation. We identify all three systems either as UX UMa-type novalike variables or as Z Cam-type dwarf novae. Our identification of these four new systems underlines that the currently known sample of CVs is rather incomplete even for bright objects. The four new systems add to the clustering of orbital periods in the 3-4 h range found in the sample of HQS selected CVs, and we discuss the large incidence of magnetic CVs and VY Scl/SW Sex stars found in this period range among the known population of CVs.