Observations of three pre-cataclysmic variables from the Edinburgh-Cape Blue Object Survey

Abstract

We present light curves and time-resolved spectroscopy of the three candidate pre-cataclysmic binaries EC 12477-1738, EC 13349-3237, and EC 14329-1625. We determine the orbital period for EC 12477-1738 as 0.362 d, thus confirming the value previously reported. A similar period, P=0.350 d, is found for EC 14329-1625. Both systems incorporate a medium-hot white dwarf (T = 15000-20000 K) and an M3V secondary star. The third pre-CV, EC 13349-3237, is the youngest of the three, with a hot WD (T ~ 35000 K), and it also has the longest period P=0.469 d. It furthermore turns out to be one of the still rare pre-CVs with a comparatively early-type, M1V, secondary star, which will eventually evolve into a CV above the period gap.