High speed photometry of faint cataclysmic variables - VI. Car2, V1040 Cen, Ha 075648, IL Nor (Nova Nor 1893), HS Pup (Nova Pup 1963), SDSS J2048-06, CSS 081419-005022 and CSS 112634-100210

We have observed 8 faint cataclysmic variable stars photometrically. The nova-like Car2 was extensively sampled but showed little variability. V1040 Cen was observed near the end of a dwarf nova outburst and possessed dwarf nova and quasi-periodic oscillations. Ha 075648 has strong large amplitude flickering and a possible orbital modulation at 3.49 h. The correct identification for the nova remnant IL Nor (Nova Nor 1893) has been established. HS Pup (Nova Pup 1963) has a possible orbital period of 3.244 h. SDSS J2048-06 is a low mass transfer dwarf nova that in quiescence shows slow variations at 7.67 h (though poorly sampled with our observations) and an orbital modulation at 87.26 min. The dwarf nova CSS 081419-005022 has an orbital period of 1.796 h and the eclipsing dwarf nova CSS 112634-100210 has an orbital period of 1.8581 h.Comment: 7 pages, 15 figures. Accepted for publication in MNRA

Observations of Faint Eclipsing Cataclysmic Variables

We present time-resolved photometry of six faint (V>17mag) cataclysmic variables (CVs); one of them is V849 Oph and the others are identified from the Sloan Digital Sky Survey (SDSS J0920+0042, SDSS J1327+6528, SDSS J1227+5139, SDSS J1607.02+3623, SDSS J1457+5148). The optical CCD photometric observations of these objects were performed at the T\"UB\.ITAK National Observatory (Turkey) between February 2006 and March 2009. We aimed to detect short time scale orbital variability arisen from hot-spot modulation, flickering structures which occur from rapid fluctuations of material transferring from red star to white dwarf and orbital period changes for selected short-period (P<4h) CVs at quiescence. Results obtained from eclipse timings and light curves morphology related to white dwarf stars, accretion disks and hot-spots are discussed for each system. Analysis of the short time coverage of data, obtained for SDSS J1227+5139 indicates a cyclical period change arisen from magnetic activity on the secondary star. Photometric period of SDSS J1607+3623 is derived firstly in this study, while for the other five systems light elements are corrected using the previous and new photometric observations. The nature of SDSS J1457+5148 is not precisely revealed that its light curve shows any periodicity that could be related to the orbital period

The new AM CVn star in Hydra

High speed photometry of the new AM CVn star in Hya (previously known as SN2003aw), spectroscopically identified by Chornock & Filippenko, shows it to have a superhump period of 2041.5 +/- 0.3 s. We find a range of brightness from V ~ 16.5 to 20.3, presumably caused by variations in the rate of mass transfer. In the intermediate state the system cycles in brightness with a period of ~ 16 h and range >= 0.4 mag. There are sidebands to the principal frequencies in the Fourier transform which have constant frequency difference from the superhump harmonics.Comment: 5 pages, 6 figures. Accepted for publication in MNRA

Spectroscopy and near-infrared photometry of the helium nova V445 Puppis

Nova Puppis 2000 (V445 Pup) has been proposed as the first example of a helium nova. Recent optical spectroscopy of V445 Pup at V=19.91 mag obtained with IMACS on the 6.5-m Magellan telescope, shows that the spectrum consists of HeI, [OI], [OII] and [OIII] emission lines and no hydrogen is present. The spectroscopy shows an expanding nova shell with blue- and redshifted velocity components around +/- 850 km/s and +/- 1600 km/s. Images taken with Magellan under very good seeing conditions (FWHM ~ 0.6") shows V445 Pup to be extended (full width at zero intensity ~ 1.9") and elongated (position angle ~ 150deg). We have followed the secular evolution of V445 Pup since the decline from (optical) maximum, at near-infrared wavelengths (J, H and Ks) using the Infrared Survey Facility (IRSF) at the Sutherland site of the South African Astronomical Observatory. We find that V445 Pup is still covered by a dense dust shell more than three years after its outburst.Comment: 2 pages, 1 figure. To appear in `The Astrophysics of Cataclysmic Variables and Related Objects', eds. J.M. Hameury and J.P. Lasota (ASP Conf. Ser.

Rapid Oscillations in Cataclysmic Variables, and a Comparison with X-Ray Binaries

We compare some of the properties of rapid oscillations in cataclysmic variables and X-Ray binaries. In addition to the earlier recognition that both types possess the same correlation between high and low frequency quasi-periodic oscillations, we have now found that the dwarf nova VW Hyi in its late stages of outburst shows the 1:2:3 oscillations harmonics that are seen in some neutron star and black hole X-Ray binaries. We point out that the behaviour of the dwarf nova WZ Sge has some similarities to those of accreting millisecond pulsars.Comment: 10 pages, 4 figures (needs AIP style file). To appear in the conference proceedings of `Interacting Binaries: Accretion, Evolution & Outcomes' (Cefalu, July 4-10 2004