HS0139+0559


This is one of the systems where long-term monitoring is absolutely crucial to determine the true CV subtype. We have obtained spectroscopy and photometry on a number of occasions, and it looked always like a UX UMa star, i.e. with a hot thick disc spectrum. The best guess is that it is either a UX UMa novalike or a Z Cam dwarf nova that we observed always during standstills. Almost no orbital photometric variability, but a nice sinusoidal radial velocity curve with a period of 243min. Monitoring is necessary to tell whether this is indeed a novalike, which is always bright (and, possibly does show some deep low states, as the VY Scl stars), or if it is a Z Cam dwarf nova which we just happened to observe always in outburst or standstill.

There is a group of three objects of this kind, HS0139+0559, and HS0229+8016, and HS0642+5049. Finding out their true nature would be a nice project.
finding chart


Literature
Aungwerojwit, A., Gänsicke, B.T., Rodriguez-Gil, P., Hagen, H.-J., Harlaftis, E.T., Papadimitriou, C., Lehto, H., Araujo-Betancor, S., Heber, U., Fried, R.E., Engels, D., Katajainen, S., 2005. HS0139+0559, HS0229+8016, HS0506+7725, and HS0642+5049: Four new long-period cataclysmic variables, A&A 443, 995

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