Bibcode
Aungwerojwit, A.; Gänsicke, B. T.; Rodríguez-Gil, P.; Hagen, H.-J.; Harlaftis, E. T.; Papadimitriou, C.; Lehto, H.; Araujo-Betancor, S.; Heber, U.; Fried, R. E.; Engels, D.; Katajainen, S.
Bibliographical reference
Astronomy and Astrophysics, Volume 443, Issue 3, December I 2005, pp.995-1005
Advertised on:
12
2005
Journal
Citations
32
Refereed citations
28
Description
We present time-resolved optical spectroscopy and photometry of four
relatively bright (V˜14.0-15.5) 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, 243.69±0.49 min, 232.550±0.049 min,
212.7±0.2 min, and 225.90±0.23 min are determined from
radial velocity and photometric variability studies. HS 0506+7725 is
characterised by strong Balmer and He emission lines, short-period
(~10-20 min) flickering, and weak X-ray emission in the ROSAT All Sky
Survey. The detection of a deep low state (B≃18.5) 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.