Sproats, Lee Nigel; (1998) Infrared and optical observation of faint cataclysmic variables. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

Distances to a sample of 36 optically faint cataclysmic variable stars (CVs), mostly lying at high Galactic latitudes, are determined from infrared photometry. I find that most lie within z 400 pc and only two stars are convincingly at Halo distances. The range of quiescent absolute V magnitudes for my sample of short period dwarf novae are found to extend to fainter magnitudes than previously believed, suggesting the quiescent mass accretion rates in these systems are low. Many of these systems have large outburst amplitudes and I show there is a relationship between outburst amplitude and quiescent V absolute magnitude. An underused alternative method to estimate distances to dwarf novae which uses absolute V magnitude at maximum as a "standard candle" is discussed. I find this method gives a more well constrained estimate to the distances than was previously achieved when using the quiescent V magnitude. I apply the alternative distance method to dwarf novae relevant to the thesis and find a number of potential Halo members. The source of CV data used to compile the original high Galactic latitude CV sample has now been superceded by a more extensive catalogue. I have searched this relatively recent publication for additional high Galactic latitude stars to supplement the original sample. I find a total of 60 CV of various sub- types, and their properties are discussed. The results of optical CCD time resolved photometry of seven poorly studied faint CV is presented. The orbital period is measured for two of the CV. Three systems show variability but with no periodicity. I find one CV exhibits no variability. An eclipse is observed for one star and a linear ephemeris is generated. Distances and quiescent absolute V magnitudes are estimated for these systems and the results discussed.

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