A spectroscopic analysis of the eclipsing nova-like EC 21178−5417 – discovery of spiral density structures

Abstract

We present phase-resolved optical spectroscopy of the eclipsing nova-like cataclysmic variable EC 21178−5417 obtained between 2002 and 2013. The average spectrum of EC 21178−5417 shows broad double-peaked emission lines from He II 4686 Å (strongest feature) and the Balmer series. The high-excitation feature, C III/N III at 4640–4650 Å, is also present and appears broad in emission. A number of other lines, mostly He I, are clearly present in absorption and/or emission.