EC-19314-5915 - A BRIGHT, ECLIPSING CATACLYSMIC VARIABLE FROM THE EDINBURGH-CAPE BLUE OBJECT SURVEY

A deeply eclipsing cataclysmic variable, with an orbital period of 4.75 hr, has been discovered in the southern Edinburgh-Cape Blue Object Survey. The star, EC 19314 - 5915, lies close to the positional constraints of a previously unidentified HEAO-1 hard X-ray source, 1H1930 - 589. Its optical spectrum is unusual in that it shows, apart from the emission lines characteristic of a nova-like, or dwarf nova cataclysmic variable (Balmer, He I and He II), metallic absorption lines typical of a late-G star. These lines come from a probable third stellar component in the system: a G8 dwarf, which contributes approximately 23 per cent of the light at B. The individual time-resolved spectra, with the tertiary absorption lines removed, show absorption reversals in the Balmer emission lines, increasing in strength for the higher series. The Balmer emission radial velocities are therefore severely distorted in comparison to the He II lambda-4686-angstrom emission and He I lambda-4471-angstrom absorption radial velocity curves. While dynamical solutions based on the emission lines are problematic, as in most CVs, a consistent result for this system is derived using the He I lambda-447 1-angstrom absorption-line radial velocity amplitude. An independent distance estimate of approximately 600 pc is derived for EC19314 - 5915, from the spectroscopic parallax of the third star.