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We report the discovery and analysis of PTF1 J085713+331843, a new eclipsing post common-envelope detached white-dwarf red-dwarf binary with a 2.5h orbital period discovered by the Palomar Transient Factory. ULTRACAM multicolour photometry over multiple orbital periods reveals a light curve with a deep flat-bottomed primary eclipse and a strong reflection effect. Phase-resolved spectroscopy shows broad Balmer absorption lines from the DA white dwarf and phase-dependent Balmer emission lines originating on the irradiated side of the red dwarf. The temperature of the DA white dwarf is $T_mathrm{WD} = 25700 pm 400,$K and the spectral type of the red dwarf is M3-5. A combined modelling of the light curve and the radial velocity variations results in a white dwarf mass of $M_mathrm{WD} = 0.61^{+0.18}_{-0.17}, mathrm{M_{odot}}$ and radius of $R_mathrm{WD} = 0.0175^{+0.0012}_{-0.0011}, mathrm{R_{odot}}$, and a red dwarf mass and radius of $M_mathrm{RD} = 0.19^{+0.10}_{-0.08}, mathrm{M_{odot}}$ and $R_mathrm{RD} = 0.24^{+0.04}_{-0.04}, mathrm{R_{odot}}$. The system is either a detached cataclysmic variable or has emerged like from the common envelope phase at nearly its current orbital period. In $sim70,$Myr, this system will become a cataclysmic variable in the period gap.
We present time-resolved optical spectroscopy of V458 Vulpeculae (Nova Vul 2007 No. 1) spread over a period of 15 months starting 301 days after its discovery. Our data reveal radial velocity variations in the HeII {lambda}5412 and HeII {lambda}4686
Binary evolution theory predicts that accreting white dwarfs with sub-stellar companions dominate the Galactic population of cataclysmic variables (CVs). In order to test these predictions, it is necessary to identify these systems, which may be diff
Four newest CCD eclipse timings of the white dwarf for polar UZ Fornacis and Six updated CCD mid-eclipse times for SW Sex type nova-like V348 Puppis are obtained. The detailed O-C analyses for both CVs inside period gap are made. Orbital period incre
We present high speed photometry and high resolution spectroscopy of the eclipsing post common envelope binary QS Virginis (QS Vir). Our UVES spectra span multiple orbits over more than a year and reveal the presence of several large prominences pass
The population of non magnetic cataclysmic variables evolving under the influence of a circumbinary disk is investigated for systems above the upper edge of the period gap at orbital periods greater than 2.75hr. For a fractional mass input rate into