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

TL;DR

This study presents detailed observations of three pre-cataclysmic binary systems, confirming their orbital periods and stellar characteristics, and highlights the diversity in their evolutionary stages and component types.

Contribution

First detailed spectroscopic and photometric analysis of three pre-CV candidates from the Edinburgh-Cape survey, including orbital periods and stellar parameters.

Findings

Confirmed orbital periods for two systems (0.362 d and 0.350 d).

Identified a hotter white dwarf in the third system (~35000 K).

Discovered a rare early-type secondary star in one pre-CV.

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.