2007MNRAS.382.1145S

Continuing our work from Paper I we present medium-resolution spectroscopy and broad-band photometry of seven cataclysmic variables (CVs) discovered by the Sloan Digital Sky Survey (SDSS). For six of these objects we derive accurate orbital periods, all which are measured for the first time. For SDSSJ013132.39-090122.2, which contains a non-radially pulsating white dwarf, we find an orbital period of 81.54±0.13min and a low radial velocity variation amplitude indicative of an extreme mass ratio. For SDSSJ205914.87-061220.4, we find a period of 107.52±0.14min. This object is a dwarf nova and was fading from its first recorded outburst throughout our observations. Isaac Newton Telescope (INT) photometry of SDSSJ155531.99-001055.0 shows that this system undergoes total eclipses which are 1.5mag deep and occur on a period of 113.54±0.03min. A Nordic Optical Telescope (NOT) light curve of SDSSJ075443.01+500729.2 shows that this system is also eclipsing, on a period of 205.965±0.014min, but here the eclipses are V shaped and only 0.5mag deep. Its low emission-line strengths, orbital period and V-shaped eclipse unambiguously mark it as a nova-like object. William Herschel Telescope (WHT) photometry of SDSSJ005050.88+000912.6 and SDSSJ210449.94+010545.8 yields periods of 80.3±2.2 and 103.62±0.12min, respectively. Photometry of the seventh and final system, SDSSJ165658.12+212139.3, shows only flickering. Our results strengthen the conclusion that the faint magnitude limit of the SDSS spectroscopic data base implies that the sample of CVs contained in it has quite different characteristics to previously studied samples of these objects. Five of the six orbital periods measured here are shorter than the observed 2-3h CV period gap. Two systems have periods very close to the minimum orbital period for hydrogen-rich CVs.