Distances and Absolute Magnitudes of a Sample of Faint Cataclysmic Variables

Abstract

Our current knowledge of the basic characteristics of CVs, such as their distance and luminosity, are largely based on observations of optically bright (V < 16 mag) systems. This has tended to favour the more luminous members (M _v ~ 7...10 mag) lying nearby in the Galactic plane (z < 400 pc). In order to alleviate this bias, Howell & Szkody (1990) compiled a list of ~90 CVs that were faint enough and were at high galactic latitude to potentially place them well outside the Galactic plane, in the halo. We have obtained infrared J and Z band images of a number of the CVs listed by Howell & Szkody (1990) in order to establish whether these systems are truely at large distances, or are instead a population of intrinsically faint objects lying relatively nearby. The distances were determined using Bailey’s method (1982) and incorporated the recent S _K calibrations by Ramseyer (1994).